Parliamentary sovereignty is the UK constitutional principle that Parliament is the supreme legal authority, so it can make or repeal any law and no court, including the UK Supreme Court, can invalidate an Act of Parliament. It explains why the UK lacks American-style judicial review.
Parliamentary sovereignty is the foundational principle of the UK's uncodified constitution. It says Parliament is the highest legal authority in the country. Parliament can pass, change, or repeal any law it wants, no Parliament can permanently bind a future Parliament, and no other institution, including the courts, can overturn an Act of Parliament.
Here's the part that matters most for AP Comp Gov. The UK Supreme Court (created in 2009) can interpret laws and rule on whether government actions are legal, but it cannot strike down a law Parliament has passed. Compare that to Nigeria, where constitutional supremacy lets the Supreme Court invalidate laws that conflict with the constitution. Parliamentary sovereignty is the reason the UK judiciary's power has a hard ceiling, which is exactly the kind of structural difference Topics 2.8 and 2.9 want you to explain.
This term lives in Unit 2 (Political Institutions), specifically Topics 2.8 (Judicial Systems) and 2.9 (Independent Judiciaries). It supports AP Comp Gov 2.8.A (describing how judiciaries function differently across course countries) and AP Comp Gov 2.9.A (explaining judicial independence relative to other institutions). Per PAU-3.H.1, a judiciary's independence partly depends on its authority to overrule legislative action. Parliamentary sovereignty is the UK's answer to that question, and the answer is 'almost none over Acts of Parliament.' That makes the UK your go-to contrast case whenever a question compares judicial power across the six course countries. The 2019 prorogation ruling against Boris Johnson shows the nuance, since the Court checked the executive's action without touching Parliament's supremacy.
Keep studying AP Comparative Government Unit 2
Judicial Review (Unit 2)
These two principles are basically opposites. Judicial review means courts can strike down laws that violate a constitution, like Nigeria's Supreme Court does. Parliamentary sovereignty means no court can do that to an Act of Parliament. A country's constitution is either supreme over the legislature or it isn't, and the UK chose the legislature.
Rule of Law (Unit 2)
The UK shows you can have strong rule of law without judicial review. Courts hold the government accountable to existing law, as in the 2019 prorogation case, even though they can't veto Parliament itself. Don't assume 'no judicial review' means 'no rule of law.' China is the contrast there, with rule by law under the CPC.
Devolution (Unit 2)
Parliament handed powers to Scotland, Wales, and Northern Ireland, but sovereignty means it could legally take them back. Devolved power is delegated, not constitutionally guaranteed. That's a sharp contrast with Nigeria's federalism, where states have constitutionally protected authority.
Prime Minister (Unit 2)
Because the PM usually commands a majority in the House of Commons, parliamentary sovereignty often works out to government dominance in practice. The party that controls Parliament effectively controls the supreme lawmaking power, which is why UK PMs with big majorities can move legislation fast.
Multiple-choice questions love using parliamentary sovereignty as the explanation for why the UK Supreme Court is structurally weaker than Nigeria's, or as the tension behind the 2019 prorogation ruling (the Court checked the executive, not Parliament). On the free-response side, the 2025 SAQ asked you to compare limits on judicial power in two course countries, and parliamentary sovereignty is the cleanest possible UK answer. The skill being tested is comparison. Be ready to state that UK courts cannot invalidate Acts of Parliament, then contrast that with a country where courts can (Nigeria) or where courts are subordinate to a party (China) or to religious authority (Iran).
Judicial review is the power of courts to strike down laws that violate a constitution. Parliamentary sovereignty makes that impossible for Acts of Parliament, because Parliament outranks everything, including any single court ruling. The UK Supreme Court can review whether government actions are lawful (that's how it blocked Johnson's prorogation in 2019), but it cannot void a statute. Nigeria's Supreme Court can, because Nigeria has constitutional supremacy instead. If an exam question asks why a UK court 'can't strike down a law,' parliamentary sovereignty is the answer, not weak judges.
Parliamentary sovereignty means the UK Parliament is the supreme legal authority and can make or repeal any law without being overruled.
The UK Supreme Court cannot strike down an Act of Parliament, which is the biggest structural limit on UK judicial power and a perfect FRQ comparison point.
The 2019 prorogation ruling shows UK courts can still check the executive's actions even though they can't override Parliament's laws.
Nigeria is the clean contrast case, since constitutional supremacy there lets the Supreme Court invalidate unconstitutional laws.
Devolution doesn't break sovereignty, because Parliament delegated those powers and legally retains the right to reclaim them.
Parliamentary sovereignty proves a state can maintain rule of law without judicial review, unlike China's rule by law under the CPC.
It's the UK principle that Parliament is the supreme legal authority, meaning it can make or repeal any law and no court or other body can overturn an Act of Parliament. It's tested in Unit 2, Topics 2.8 and 2.9, as the main limit on UK judicial power.
No. Because of parliamentary sovereignty, the UK Supreme Court (established 2009) cannot invalidate an Act of Parliament. It can interpret statutes and rule government actions unlawful, but Parliament's laws stand.
No, it actually protected it. The Court ruled that Boris Johnson's suspension of Parliament was unlawful because it blocked Parliament from doing its job. The judiciary checked the executive on Parliament's behalf, which is exactly why the exam uses this case to illustrate judicial independence in a democracy.
Judicial review lets courts strike down laws that violate a constitution, like Nigeria's Supreme Court does. Parliamentary sovereignty rules that out for the UK, since Parliament outranks the courts. The two principles are essentially mirror images of where ultimate legal authority sits.
No. Parliament delegated powers to Scotland, Wales, and Northern Ireland, but it legally retains the authority to alter or revoke them. That's why UK devolution is different from Nigerian federalism, where state powers are constitutionally protected.