Notes · PoliticsUK · A-Levels

Comparative Politics: UK and USA

Comparative politics relates the UK and US systems to one another, using the structural, rational and cultural approaches to explain their similarities and differences. This topic examines the comparative approaches and applies them to compare the two constitutions, legislatures, executives, judiciaries, and systems of democracy, parties and pressure groups - the distinctive comparative demand of the specification.

5 sections~24 min reading time3 competenciesLevel Foundation 1 · Standard 3 · Advanced 1

T·181818 / 18

Exam profile

AO1 · Demonstrate knowledge of the UK and US systems and of the structural, rational and cultural comparative approachesAO2 · Analyse the similarities and differences between the two systems and apply a comparative approachAO3 · Evaluate the significance of the comparisons and which approach best explains them, reaching a substantiated judgement

Operators:explain and analyseevaluateto what extentanalyse and evaluate this statementexamine

basic level

AS-Level expects the main similarities and differences between the UK and US systems.

higher level

The full A-Level requires the comparative approaches (structural, rational, cultural) to be applied and evaluated, reaching a judgement.

Depth

Text

Contents · 5 sections

Comparative Politics: UK and USA

The comparative approaches: structural, rational and cultural#

FoundationAQA 7152/2: Comparative politicsDfE GCE Politics subject content

The three comparative approaches

Fig. 1The structural, rational and cultural approaches explain similarities and differences by institutions, incentives and values respectively.

Comparative politics is the systematic comparison of political systems - here, the UK and USA - and the specification requires not just noticing similarities and differences but explaining them using three comparative approaches (or theories). These approaches are ways of accounting for WHY two systems are similar or different, and deploying them is the distinctive analytical demand of the comparative paper. The three approaches are the structural (or institutional) approach, the rational approach, and the cultural approach. A strong answer can define each, apply it to a comparison, and assess which best explains a given similarity or difference.

The structural (institutional) approach explains political behaviour and outcomes by reference to the structures and institutions of a political system - its constitution, its institutions, and the processes and rules within which political actors operate. On this approach, the differences between the UK and USA are explained by their different institutional arrangements: the US separation of powers and codified, entrenched constitution versus the UK's fusion of powers and uncodified, flexible constitution shape how each system behaves. The structural approach directs attention to how the design of institutions determines what happens - for example, explaining US gridlock by the separation of powers and the many veto-points.

The rational approach explains political behaviour by reference to the self-interested, rational calculations of individual political actors - politicians, voters, groups - who pursue their goals (re-election, power, policy) strategically within the incentives they face. On this approach, differences between the systems are explained by the different incentives actors face: US legislators, facing frequent elections in a candidate-centred system, behave differently from UK MPs facing party discipline, because their rational self-interest points in different directions. The rational approach directs attention to how individuals calculate and respond to incentives, explaining behaviour as strategic choice.

The cultural approach explains political behaviour by reference to the shared ideas, values, beliefs and culture of a society - the norms and attitudes that shape how people think about politics. On this approach, differences between the UK and USA are explained by their different political cultures: the American emphasis on individualism, liberty, distrust of government and rights, versus a British political culture with different traditions and attitudes to the state, authority and the constitution. The cultural approach directs attention to how deep-seated values shape political behaviour and institutions - for example, explaining the strength of rights-based, individualist politics in the USA by American political culture. A good answer can apply each approach and, crucially, judge which best explains a particular comparison - the higher-level skill the comparative essays reward.

Worked example

Applying the three approaches to one difference

Use the three approaches to explain why US legislators are less loyal to their party than UK MPs.

Structural
The separation of powers means US legislators are elected independently of the executive and chosen through primaries, so the party leadership has little institutional hold over them - unlike the UK's fused system and whips.
Rational
US legislators, facing frequent elections and primary challenges, rationally prioritise their own re-election and constituents over party loyalty; UK MPs' careers depend on party favour, so loyalty is rational for them.
Cultural
A US political culture that prizes individualism and is suspicious of concentrated party power may reinforce weaker party loyalty; British culture is more accepting of strong, disciplined parties.
Judge the approaches
The structural and rational approaches (institutions and incentives) explain most of the difference here, with culture reinforcing it - so a strong answer weighs them rather than treating them as equal.

Result: The weaker party loyalty of US legislators is best explained by the structural approach (separation of powers, primaries) and the rational approach (re-election incentives), with the cultural approach (individualism) reinforcing it - illustrating how the three approaches combine, and how a strong answer judges which explains most.

Typical mistakes

Confusing the three approaches - structural (institutions), rational (individual incentives), cultural (values).
Listing the approaches without APPLYING them to explain a specific comparison, which is the comparative demand.

Active revision

Explain and analyse the three comparative approaches used to study the UK and US political systems. (9 marks)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for politics (Department for Education)

Comparing the constitutions and sovereignty#

StandardAQA 7152/2: Comparative politicsDfE GCE Politics subject content

The UK and US constitutions compared

Fig. 2Both are liberal-democratic with the rule of law; they differ in form (codified/entrenched vs uncodified/flexible) and sovereignty.

The most fundamental comparison is between the two constitutions, and a strong answer draws out both the differences and the significant similarities. The central difference concerns form: the US Constitution is codified, entrenched and supreme - a single document, protected by a difficult amendment process, against which all law is tested - whereas the UK constitution is uncodified, unentrenched and flexible, drawn from many sources and changeable by an ordinary Act of Parliament. This difference in form has far-reaching consequences: the US Constitution is rigid, hard to change and guarded by the courts, while the UK constitution is flexible, easily changed and rests on the sovereignty of Parliament.

The related difference concerns sovereignty. In the USA, sovereignty is dispersed and constitutional: ultimate authority rests with the Constitution and, through it, with the people; power is divided between the branches and between the federal and state levels, all bound by the supreme law. In the UK, sovereignty rests with Parliament - the doctrine of parliamentary sovereignty makes Parliament the supreme legal authority, able to make or unmake any law. This is a deep, structural difference: the US system entrenches limits on all institutions, while the UK system leaves a sovereign Parliament legally unlimited - though, as earlier topics showed, devolution, referendums and (formerly) the EU have qualified UK sovereignty in practice.

Despite these differences there are important similarities that a good comparison notes. Both constitutions establish liberal democracies with the rule of law, regular elections, the protection of rights, and limits on government power - they pursue similar ends by different means. Both have seen their constitutions develop over time (the US through amendment and, more, through Supreme Court interpretation; the UK through statute, convention and reform), so neither is static. Both face debates about reform (the UK over codification and entrenchment; the USA over the difficulty of amendment and the power of the Court). The two constitutions are thus different in form and in the location of sovereignty but similar in their liberal-democratic purposes.

Applying the comparative approaches to the constitutional difference is the higher-level demand, and it can be argued. The structural approach explains the difference directly - the two systems have different institutional designs (codified/entrenched vs uncodified/flexible), which shape everything else. The cultural approach adds depth: the US Constitution's entrenchment and rights-focus reflect a political culture born of revolution, suspicion of government and reverence for the founding document, whereas the UK's flexible, evolutionary constitution reflects a culture of gradualism, pragmatism and trust in Parliament and precedent. The rational approach is less central here but can explain, for example, why actors defend arrangements that serve their interests. A strong answer compares the constitutions systematically (form, sovereignty, and shared liberal-democratic ends), and uses the structural and cultural approaches to explain WHY they differ, reaching a judgement about which approach best accounts for the difference - typically the structural and cultural together.

Worked example

Explaining the constitutional difference with the approaches

Use the comparative approaches to explain why the UK and US constitutions differ so fundamentally.

The difference
The US Constitution is codified, entrenched and supreme; the UK constitution is uncodified, unentrenched and flexible, resting on parliamentary sovereignty.
Structural explanation
The two systems were designed with different institutional foundations - a written founding document with entrenched limits vs an evolved, sovereign-Parliament system - which shape everything else.
Cultural explanation
The US Constitution reflects a culture born of revolution, distrust of government and reverence for the founding text; the UK's reflects gradualism, pragmatism and trust in Parliament and precedent.
Judge the approaches
The structural approach describes the difference; the cultural approach best explains its ORIGIN - the different histories and values that produced the two designs.

Result: The fundamental constitutional difference is captured by the structural approach (codified/entrenched vs uncodified/flexible designs) but best explained by the cultural approach - the US Constitution reflecting a revolutionary culture of distrust of government and reverence for a founding text, the UK's reflecting a culture of gradualism and trust in Parliament.

Typical mistakes

Listing differences without noting the significant similarities (both liberal democracies with the rule of law and rights) or applying a comparative approach.
Confusing constitutional/dispersed sovereignty (USA) with parliamentary sovereignty (UK).

Active revision

Analyse and evaluate the significance of the differences between the UK and US constitutions. (25 marks)

Active recall

Recall the key points — then reveal.

Sources: AQA AS and A-level Politics (7152) specification (AQA)

Comparing the legislatures and executives#

StandardAQA 7152/2: Comparative politicsDfE GCE Politics subject content

Separation versus fusion of powers

Fig. 3The USA separates the executive from the legislature; the UK fuses them - the structural root of the differences between the systems.

Comparing the legislatures - Congress and Parliament - reveals a fundamental structural difference that shapes their power. The decisive contrast is between the separation of powers (USA) and the fusion of powers (UK). In the USA, Congress is separate from and independent of the executive: its members do not serve in the executive, it is separately elected, and it makes its own law, controls the purse and checks the President - so it is a genuinely powerful, independent legislature. In the UK, the executive is fused with the legislature: the government is drawn from and sits in Parliament and normally commands a Commons majority, so it dominates the legislature that is supposed to check it. This structural difference means Congress is far more powerful relative to its executive than Parliament is relative to its.

The comparison of the legislatures can be developed across several dimensions. Congress is co-equal with the executive and often in conflict with it; Parliament is usually dominated by the executive it sustains. Congress has powerful, independent committees and weak party discipline; Parliament has weaker committees (though strengthening) and strong party discipline through the whips. Congress's bicameral chambers (House and Senate) are broadly co-equal; the UK's are unequal (the elected Commons dominates the appointed Lords). These differences flow largely from the separation vs fusion of powers - the structural approach explains most of them - though the rational approach (different re-election incentives producing weaker US party discipline) and the cultural approach add to the account.

Comparing the executives - the President and the Prime Minister - reveals a parallel set of differences. The President is a separately elected head of state and government, secure for a fixed term, who sits OUTSIDE the legislature and must bargain with a Congress he cannot command; the Prime Minister is the leader of the majority party INSIDE Parliament, not separately elected as PM, removable by the party at any time, who normally commands the legislature through the majority and the whips. So the President has an independent electoral mandate and security of tenure but weaker control over the legislature, while the PM lacks a personal mandate and fixed term but usually dominates the legislature - a striking contrast in the sources and limits of executive power.

Applying the comparative approaches to the executive comparison is the higher-level demand. The structural approach explains the core difference: the separation of powers gives the President independence from but weak command over the legislature, while the fusion of powers gives the PM command over but dependence on the legislature. The rational approach explains behaviour within these structures - a President bargains because he must, a PM manages his party because his tenure depends on it. The cultural approach can explain, for example, the more personalised, presidential style of leadership in the USA. A strong answer compares the executives on their sources and limits of power (mandate, tenure, relationship with the legislature) and uses the structural approach above all to explain the differences - concluding, for instance, that the President is more independent but more constrained by the legislature, while the PM is more dependent on the party but more dominant over the legislature, a difference rooted in separation versus fusion of powers. This is also the material for the earlier presidentialisation debate, showing how the topics connect.

Worked example

Comparing the President and the Prime Minister

Compare the sources and limits of power of the US President and the UK Prime Minister.

The President's power
A separate national mandate and a fixed term give the President independence and security, but the separation of powers means he cannot command Congress and must bargain.
The PM's power
No personal mandate or fixed term (removable by the party), but the fusion of powers and a Commons majority let the PM normally command the legislature.
The trade-off
The President is more independent but more constrained by the legislature; the PM is more dependent on the party but more dominant over the legislature.
The structural explanation
The difference flows from separation vs fusion of powers - the structural approach best explains it.

Result: The President is more independent (separate mandate, fixed term) but more constrained by the legislature (separation of powers), while the PM is more dependent on the party (no fixed term) but more dominant over the legislature (fusion of powers) - a contrast in the sources and limits of executive power best explained by the structural approach.

Typical mistakes

Muddling the two systems - Congress is independent of the executive (separation); the UK government sits in and dominates Parliament (fusion).
Comparing without applying a comparative approach, or missing that the President is more independent but more constrained by the legislature than the PM.

Active revision

Analyse and evaluate the view that the US President is more constrained than the UK Prime Minister. (25 marks)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for politics (Department for Education)

Comparing the judiciaries, democracy and pressure groups#

StandardAQA 7152/2: Comparative politicsDfE GCE Politics subject content

Congress and Parliament compared

Fig. 4Both legislate, represent and scrutinise; Congress is independent and powerful (separation), Parliament executive-dominated (fusion).

Comparing the two judiciaries brings out a decisive difference rooted in the constitutions. The US Supreme Court can strike down Acts of Congress, executive actions and state laws as unconstitutional (judicial review of the constitution), because it interprets a codified, entrenched, supreme Constitution - making it a co-equal, immensely powerful branch. The UK Supreme Court cannot strike down an Act of Parliament, because Parliament is sovereign; it can review the legality of executive action (judicial review) and, under the Human Rights Act, issue declarations of incompatibility, but it cannot invalidate statute. So the US Court is far more powerful relative to the elected branches than the UK Court - a difference the structural approach explains directly (codified/entrenched vs uncodified/sovereign-Parliament). Both, however, are independent judiciaries that check the executive and protect rights, so they share important functions.

Comparing democracy and elections reveals both similarities and differences. Both systems are liberal democracies with regular, free elections, but they differ in their electoral arrangements: the USA elects its President through the winner-take-all Electoral College and uses primaries to choose candidates, while the UK elects a government through FPTP in single-member constituencies (with proportional systems for devolved bodies), and party leaders are chosen internally. Both are dominated by two major parties sustained by their winner-take-all electoral systems, and both have seen rising partisanship - similarities the structural approach (the effect of winner-take-all systems) explains well. But US parties are more decentralised and candidate-centred, and US politics is more polarised - differences the cultural and rational approaches help explain.

Comparing pressure groups shows a difference of degree and access. In both systems pressure groups seek to influence government and both face the pluralism-vs-elitism debate. But US interest groups are more numerous and powerful, because the fragmented US system (separation of powers, federalism, weak parties, the courts) offers far more access points than the more centralised, executive-dominated UK system, and because the vast role of money (post-Citizens United) magnifies their influence. So while pressure-group politics is important in both, it is more central, better-funded and more litigation-based in the USA - a difference the structural approach (access points) explains, with the role of money adding a rational/cultural dimension.

Across all these comparisons a pattern emerges that a strong answer draws out: most of the differences between the UK and USA flow from the single structural difference between the separation of powers with a codified, entrenched constitution (USA) and the fusion of powers with parliamentary sovereignty (UK). This structural difference makes the US system more fragmented, with more independent and powerful institutions (Congress, the Court, interest groups) checking one another, and the UK system more centralised, with the executive dominating a sovereign Parliament. The rational approach (actors responding to the different incentives each system creates) and the cultural approach (the different political values and histories of the two nations) add depth and explain particular features, but the structural approach is usually the most powerful. Recognising this pattern - and being able to judge which approach best explains a given comparison - is the key to the higher-level comparative essays.

Worked example

Why the US Supreme Court is more powerful than the UK's

Compare the power of the US and UK Supreme Courts and explain the difference.

The US Court
Can strike down Acts of Congress, executive actions and state laws as unconstitutional, because it interprets a codified, entrenched, supreme Constitution - a co-equal branch.
The UK Court
Cannot strike down an Act of Parliament (Parliament is sovereign); it reviews executive action and issues declarations of incompatibility, but cannot invalidate statute.
The shared feature
Both are independent judiciaries that check the executive and protect rights - similar functions, different power over the legislature.
The structural explanation
The difference flows directly from the constitutions - a codified, entrenched supreme law (USA) vs an uncodified constitution with parliamentary sovereignty (UK) - the structural approach.

Result: The US Supreme Court is far more powerful than the UK's because it can strike down statute under a codified, entrenched, supreme Constitution, whereas the UK Court cannot invalidate an Act of a sovereign Parliament - a difference best explained by the structural approach, though both remain independent, rights-protecting judiciaries.

Typical mistakes

Saying the UK Supreme Court can strike down laws - it cannot; only the US Court can strike down statute (under an entrenched constitution).
Comparing feature by feature without drawing out the underlying structural pattern or applying the approaches.

Active revision

Analyse and evaluate the view that the differences between the UK and US systems are best explained by the structural approach. (25 marks)

Active recall

Recall the key points — then reveal.

Sources: AQA AS and A-level Politics (7152) specification (AQA)

Applying a comparative approach: reaching a judgement#

AdvancedAQA 7152/2: Comparative politicsDfE GCE Politics subject content

Applying the comparative approaches

Fig. 5Strong comparison combines the approaches and judges their weight - the structural approach usually explains most, reinforced by the rational and cultural.

The distinctive skill of the comparative paper is not merely to describe similarities and differences but to ANALYSE them using a comparative approach and to EVALUATE which approach best explains them, reaching a judgement - and a top answer makes this its organising principle. A weak comparative answer lists parallel facts about the two systems; a strong one selects significant comparisons, explains them through the structural, rational and cultural approaches, weighs which approach explains best, and reaches a substantiated conclusion. The approaches are the tools that turn a description into an argument, and using them well is what the comparative essays reward.

Applying the approaches requires judgement about which fits a given comparison, because they are not equally powerful in every case. For many of the deepest differences between the UK and USA - the power of Congress and the Court, the constraints on the executive, the strength of interest groups - the structural approach is usually the most powerful, because these differences flow from the fundamental institutional contrast between the separation of powers with a codified constitution and the fusion of powers with parliamentary sovereignty. For differences in political behaviour within those structures - why US legislators are less party-loyal, why turnout or participation differs - the rational approach (actors responding to different incentives) often adds most. For deep-seated differences in values and style - American individualism, rights-consciousness and distrust of government, the more personalised US leadership - the cultural approach best explains the origins.

The strongest answers often combine the approaches while judging their relative weight, rather than treating them as rival, all-or-nothing explanations. Most real comparisons are best explained by more than one approach acting together: the weaker party discipline of US legislators, for example, is explained structurally (separation of powers, primaries), rationally (re-election incentives) and culturally (individualism) at once. The analytical skill is to apply the relevant approaches, show how they combine, and judge which carries most weight for the particular comparison - concluding, for instance, that a difference is 'primarily structural but reinforced by culture'. This nuanced use of the approaches, rather than a mechanical labelling, is what distinguishes a top-band comparative answer.

Reaching an overall judgement means stepping back to assess the significance of the comparison and the best explanation of it. A common and defensible overall conclusion is that the UK and USA are both liberal democracies pursuing similar ends - the rule of law, representative government, rights, limited power - by structurally very different means, and that the great majority of their differences flow from the single structural choice between the separation of powers with an entrenched constitution and the fusion of powers with parliamentary sovereignty; so that the structural approach is usually the most powerful explanation, with the rational and cultural approaches adding essential depth and explaining behaviour and origins. The essential skills the comparative paper tests are therefore: to compare systematically, to apply the three approaches, to judge which best explains each comparison, to combine them where appropriate, and to reach a clear, substantiated judgement - the same evaluative discipline demanded throughout A-Level Politics, now applied across two systems. A strong answer demonstrates all of these, arguing a clear line to a conclusion rather than listing parallel facts.

Worked example

Model essay plan: are the differences best explained by institutions?

Plan a 25-mark answer evaluating whether the differences between the UK and US systems are best explained by their institutions (the structural approach).

Introduction and thesis
Note the three approaches; signal a judgement - the structural approach is usually the most powerful, but the rational and cultural add essential depth. Frame the comparison.
The structural case
The power of Congress and the Court, the constraints on the executive, the strength of interest groups - all flow from separation of powers + codified constitution (USA) vs fusion + parliamentary sovereignty (UK).
The rational contribution
Behaviour within the structures - weaker US party discipline, different participation - is best explained by actors' responses to different incentives (re-election, primaries).
The cultural contribution
Deep differences in values and style - American individualism, rights-consciousness, distrust of government, personalised leadership - are best explained by the two nations' political cultures and histories.
Judgement
Conclude that the structural approach explains most of the fundamental differences, but that the rational and cultural approaches are essential for behaviour and origins - so the differences are 'primarily structural but reinforced by incentives and culture'.

Result: A top-band plan argues that the structural approach best explains the fundamental institutional differences (power of Congress and the Court, the executive, interest groups), while the rational approach explains behaviour within those structures and the cultural approach explains their origins - judging the differences 'primarily structural but reinforced by incentives and culture', a combined, weighted conclusion rather than a single-approach answer.

Typical mistakes

Listing parallel facts about the two systems without applying or evaluating a comparative approach - the most common comparative-essay failing.
Treating the approaches as rival, all-or-nothing explanations rather than combining them and judging their relative weight.

Active revision

'The differences between the UK and US political systems are best explained by their institutions.' Analyse and evaluate this statement. (25 marks)

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for politics (Department for Education)

References & sources

Sources

Department for Education

GCE AS and A level subject content for politics

AQA

AQA AS and A-level Politics (7152) specification

Comparative Politics: UK and USA

5 sections~24 min reading time3 competenciesLevel Foundation 1 · Standard 3 · Advanced 1

Comparative Politics: UK and USA

Key points

Applying the three approaches to one difference

Key points

Explaining the constitutional difference with the approaches

Key points

Comparing the President and the Prime Minister

Key points

Why the US Supreme Court is more powerful than the UK's

Key points

Model essay plan: are the differences best explained by institutions?

Sources

Comparative Politics: UK and USA

Key points

Applying the three approaches to one difference

Key points

Explaining the constitutional difference with the approaches

Key points

Comparing the President and the Prime Minister

Key points

Why the US Supreme Court is more powerful than the UK's

Key points

Model essay plan: are the differences best explained by institutions?

Sources