Criminal Activity

Foreign criminals cannot be deported if they have family in the UK. (BBC Radio 4 News.) This is because, it is said, of the European Convention on Human Rights.
But there is nothing in the Convention about immigration control; and the specific reason for setting up the Council of Europe was to prevent the excesses of the Second World War from happening again. So the very last thing it should do is enable people from non-member states to occupy member states.
Quite the contrary, in addition to there being laws galore in this area there is ample normative scope - see, eg, my blog of 17 April - for the judiciary (in light of current tensions with the legislature) to at long last "End the concession to foreign husbands and male fiances" - as promised by Mrs Thatcher in her manifesto at the time of the 1979 General Election.