Comparing Parliament and Congress

Both systems have two chambers, and there the resemblance thins out fast. The difference is in how members arrive and how long they stay.

	House of Commons	House of Lords	House of Representatives	Senate
Size	650	Over 800 as of early 2026	435	100
How members arrive	Elected by first-past-the-post	Appointed life peers, Lords Spiritual, and hereditary peers still sitting as of early 2026	Elected from districts by population	Two elected per state, regardless of population
Term	Up to five years	For life	Two years	Six years, one third elected every two years
Removable by voters	Yes	No	Yes	Yes

Two consequences follow immediately.

The Senate over-represents small states by design. Wyoming and California elect two senators each. That is entrenched in the Constitution and cannot be amended away by an ordinary majority, so it operates as a permanent structural feature of American politics.

The Lords has no electoral mandate at all. As of March 2026, around 22% of its membership sat as crossbenchers belonging to no party, the third largest group, which means no government commands an automatic majority there. Defenders of the chamber point to the expertise of its members; critics call an unelected house indefensible in a democratic age and object that its size has no upper limit.

The specification asks directly about "the extent to which each of the Houses are equal". The two systems give opposite answers.

In the USA the chambers are close to co-equal. Ordinary legislation must pass both in identical form, and each holds exclusive powers the other cannot exercise.

Exclusive to the House of Representatives	Exclusive to the Senate
Revenue bills must originate here	Ratify treaties by a two-thirds vote
Brings articles of impeachment by simple majority	Tries impeachments, conviction requiring two thirds
Elects the President if no candidate wins an electoral college majority	Confirms presidential appointments, including Supreme Court Justices and Cabinet secretaries

The Senate is generally treated as the more prestigious chamber because its terms are longer, its constituencies larger and its confirmation and treaty powers unique.

In the UK the Commons is dominant. The Lords may revise, delay and force the government to think again, but the Commons has the last word:

• The Parliament Act 1911, tightened by the Parliament Act 1949, allows a bill rejected by the Lords to become law after a delay of roughly one year, and a money bill after one month.
• The Salisbury Convention discourages the Lords from voting down a bill implementing a manifesto commitment.
• Only the Commons can force a government from office through a vote of no confidence, and by convention the Prime Minister and the great majority of senior ministers sit there. Ministers do sit in the Lords — the Leader of the House of Lords is a Cabinet post — but the government's centre of gravity is the elected chamber.

Both systems put a bill through readings, committee scrutiny and both chambers. The differences lie in who controls the timetable and how easily a bill can be killed.

Stage	UK	USA
Introduction	Mostly government bills; backbenchers get limited slots	Any member may introduce; the President cannot
Detailed scrutiny	Public bill committee, appointed to reflect the Commons party balance	Standing committee, whose chair can refuse to schedule a bill at all
Floor obstruction	Limited; the government controls most Commons time	Senate filibuster, broken only by 60 votes for cloture
Resolving differences	"Ping-pong" between the Houses until one gives way	Both chambers must agree an identical text
Final approval	Royal Assent, a formality since 1708	Presidential signature, or a veto overridable by two thirds of both chambers

Worked example — the assisted dying bill and the Lords. A private member's bill on assisted dying passed the House of Commons and then moved slowly through the Lords. In December 2025 its sponsor, Labour MP Kim Leadbeater, publicly criticised the "very slow" progress and said she had concerns the bill might run out of time. Former ministers argued that unelected peers were over-reaching. Peers replied that the bills reaching them are long and poorly drafted, that the Commons no longer scrutinises legislation in detail, and that careful scrutiny is the chamber's constitutional job. The episode shows both the reality of Lords delay and its limit: the second chamber slows a bill and makes its point, but the elected chamber expects to prevail.

Worked example — a US bill dying without a vote. The equivalent US obstruction happens earlier and more decisively. A committee chair who declines to schedule hearings can end a bill without any member voting on it, and forty-one senators can sustain a filibuster against the wishes of a majority. Where a UK government's problem is finding time, a US sponsor's problem is finding a path through several independent veto points.

The specification lists, at Paper 3A 2.2.1, the factors affecting how members of Congress vote: parties and caucuses, constituency, interest groups and lobbyists. The UK list would be much shorter, and party would sit at the top of it.

Why Westminster discipline is strong:

• Ministers are drawn from Parliament, so ambition runs through the party leadership. The payroll vote of ministers and their aides is bound by collective responsibility.
• Candidates are selected by local parties within a national framework, and the whips manage careers.
• Governments are formed and destroyed on Commons votes, so a rebellion can bring down the administration a rebel belongs to.

Why congressional discipline is weaker:

• Members are nominated in primaries by voters in their own state or district, not by the national party.
• They raise their own campaign funds, which makes interest groups and donors direct participants in their calculations.
• No member of Congress can become a Cabinet secretary while keeping their seat, so the leadership has fewer rewards to offer.
• Congressional caucuses — groups of legislators sharing an interest, such as the Congressional Black Caucus — give members an organising base independent of party leaders.

That said, partisanship in Congress has risen sharply. During the shutdown that began on 1 October 2025, both parties held together and blamed each other, with the Senate Democratic leader accusing the President of using the public as pawns and the White House casting Democrats as an obstructionist opposition. Rising polarisation is a cultural change working against a structural feature.

Both legislatures scrutinise the executive; they do it with different instruments and with different degrees of independence.

Function	UK Parliament	US Congress
Routine questioning	Departmental question times and weekly Prime Minister's Questions	No equivalent; the President appears only for the State of the Union
Investigation	Select committees shadowing each department, publishing reports	Standing and special committees with subpoena power
Financial control	Approves supply, but the government sets the Budget and expects to win	Appropriations must originate in Congress; refusal closes the government
Ultimate sanction	Vote of no confidence removes the government	Impeachment by the House, conviction by two thirds of the Senate
Opposition role	The Official Opposition leads scrutiny and holds Opposition Days	The minority party has fewer formal rights but real power in the Senate

Worked example — the power of the purse in practice. The October 2025 shutdown is the clearest available illustration of congressional independence. Congress declined to pass a funding bill, non-essential federal operations closed, and hundreds of thousands of employees were furloughed while essential services continued. Neither branch could compel the other. The comparison is that a UK government losing a supply vote would face a confidence crisis and probably a general election, so the standoff cannot persist. Congress's check is blunter but genuinely independent; Parliament's is sharper but rarely turned against a government with a majority.

Structural. This carries most of the weight. Separation of powers means members of Congress owe nothing to the executive and can vote against a President of their own party without endangering their careers. Fusion of powers means UK ministers sit in the chamber that scrutinises them and depend on its confidence. The same structural logic explains the second chambers: the Senate is elected and constitutionally entrenched, so it is powerful; the Lords is appointed and constrained by the Parliament Acts, so it is not. Electoral cycles compound this. A two-year House term keeps representatives permanently campaigning, while a five-year Commons term gives MPs long stretches without a public test.

Rational. Individual calculation explains variation within those structures. A senator facing re-election in a marginal state votes with their electorate against their party leadership because that is what preserves their seat. A UK backbencher weighs the same question and reaches the opposite answer, because at Westminster promotion runs through the leadership. Pearson's commentary on the Lords case study notes that peers "usually back down, having made their point, if the House of Commons insists" — a rational read of a chamber that knows it lacks a mandate and would rather bank a concession than lose a confrontation.

Cultural. Shared values explain what neither structure nor incentive can. Deference to the elected chamber is a cultural norm, not a legal rule: nothing in law compels the Lords to observe the Salisbury Convention. In the USA, rising partisan polarisation has changed congressional behaviour without changing a single rule, turning shutdowns and blocked nominations from rare events into recurrent ones. Congressional caucuses organised around race, gender or ideology are cultural formations operating inside a structural chamber.

1. Saying Congress is "more powerful" without qualification

Congress is more independent; Parliament is legally sovereign. Congress can block a President; Parliament can pass any law it likes, including one abolishing a devolved legislature. Say which kind of power you mean.

2. Overstating the House of Lords

The Lords delays, revises and embarrasses. It does not veto. Any answer suggesting it can block a determined government has missed the Parliament Acts.

3. Treating congressional party discipline as absent

Party is the strongest influence on how a member of Congress votes, and partisanship has risen since 2000: during the shutdown that began on 1 October 2025 both parties held together. The accurate claim is that party competes with constituency, caucuses and interest groups rather than overriding them.

4. Confusing select committees with public bill committees

Select committees investigate a department's work and publish reports. Public bill committees scrutinise a specific bill clause by clause. Issue 4 of the specification names both, so the distinction is worth making precisely.

5. Forgetting the second chamber comparison

Section 6.2.3 asks about "each of the Houses" and about the extent to which they are equal. An answer covering only Commons and House of Representatives has left out half the content.

6. Leaving the theory to the last paragraph

Attach an approach to each comparison as you make it rather than bolting a theory paragraph onto the end. The 12-mark questions in Sections A and B assess AO1 and AO2 only, so they call for explanation rather than a verdict — but the same comparative material carries 10 marks for AO3 in each Section C essay, where a substantiated judgement is required.