[vilhelm_s]

While the UK has parliamentary sovereignty, the UK is also party to the European Convention of Human Rights, which (via the Human Rights Act) takes precedence over any other law (unless a law is passed that explicitly repeals the Human Rights Act).

And indeed, in 2007 someone appealed a camera speeding ticket all the way to the European Court of Human Rights, saying that this system violates the right to remain silent!

Unfortunately, the court rejected the argument. "On the one hand, it was self-evident that it was incompatible with the immunities to base a conviction solely or mainly on the accused's silence or on a refusal to answer questions or to give evidence himself. On the other hand, the immunities could and should not prevent the accused's silence from being taken into account in situations which clearly called for an explanation. The conclusion was that the 'right to remain silent' was not absolute"

http://thenewspaper.com/news/18/1832.asp