From what I gathered from a video a long time ago:

For the UK's judiciary system, when a judge decides on a case, they have to give their reasons for it. There is also a hierarchy of the court system, i.e. parties could appeal to higher courts when they disagree with the judgement from the lower court. That provides a certain checks and limitations to the jurisdiction of the lower courts. As for judges of the highest court, they answer to people like the head of the judiciary, while the judiciary and the executive (the government) provides checks and balances among each other.

I suppose, at least the highest court judge, would be able to make an unsound judgement and let guilty people free and vice versa, but if the rationale he gives to his judgements are way to far fetch and ridiculous, they will be held accountable by the judiciary and the government.

As for US' judiciary system, the juries generally are not required to give reasons for their judgement, and can be sketchy as heck.