The scary thing for me is that in the US, the President and by extension the DoJ has a lot of power to override any legal protections that exist in most countries. In the UK, the Prime Minister or the Home Office cannot ring up any of the enforcement agencies and tell them to drop a corruption case - the law is supposed to apply to everyone.
In the US, for some reason, if you are a danger to the President's friends, you can be fired/your department can just be shutdown executively and this isn't just about Trump, it is about a serious weakness in the systems of governance.
> In the UK, the Prime Minister or the Home Office cannot ring up any of the enforcement agencies and tell them to drop a corruption case - the law is supposed to apply to everyone.
I would not rely on that. The Attorney General can withdraw prosecutions, and is a government minister (although not technically in the Cabinet).
Parliament can do anything, it just usually doesn't. This includes retroactive legislation to decide that you did not win a lawsuit that you actually did win (Reilly and Wilson v Secretary of State, although that itself was eventually ruled unlawful). The infinite delay of Bloody Sunday prosecutions is probably the biggest example in UK discourse.
No country is safe from this if enough authoritarian-collaborator political appointments are made (such as happened to SCOTUS). It should really be viewed as a form of coup.