AO1: US Constitution is codified and entrenched, UK is part-written and uncodified, coming from a wide range of sources AO2: This makes the US Constitution more structured and rigid, whereas the UK constitution is more flexible and easier to amend because there are more opportunities to amend through statute, case law, convention etc AO1: US Constitution contains a specific Bill of Rights, UK has to pass statute law to protect rights AO2: The protection of rights in the US may be easier because of the Bill of Rights and other amendments contained in the US Constitution, whereas rights may be more easily changed in the UK with the passing of new statute law AO1: US Constitution explicitly outlines the powers and limitations on the branches of government, but in the UK this is not always explicitly written down AO2: This means the system of checks and balances is more enforceable in the US than in the UK, where checks and balances have often arisen through convention and so may be more easily avoided or changed AO1: US Constitution outlines separation of powers, but UK has fusion of powers AO2: This allows each branch of government to act more independently in the US whilst still ensuring that cooperation is essential to pass legislation, whereas the UK's fusion of power can allow executive dominance and lessens the independence of the branches AO1: US Constitution outlines a federal system, whereas the UK constitution is unitary AO2: The US federal system is enshrined by the US Constitution, which protects states' rights, whereas the unitary nature of the UK government means that the Westminster government must choose to devolve power, as they have done in Scotland, Wales, Northern Ireland and some mayoral authorities.