The European Court of Human Rights is hugely important. From the right to an education to the right to vote, it covers and protects all aspects of our lives. The idea of losing it cause of some lies about “boat people” is terrifying and the effect on our lives untold.
The European Court of Human Rights enforces the European Convention on Human Rights, which is an internationally treaty that was ratified in the UK in 1951 (with enthusiastic support from Churchill). It lists a bunch of fundamental rights.
In 1998, the UK passed the Human Rights Act, which provides these protections under domestic law, with the European court acting as a backstop.
So, yes, this is domestic law.