manon
you are making the usual confusion about the echr and the eu
The first thing to do is distinguish between two courts: the European Court of Justice (ECJ) and the European Court of Human Rights (ECHR).
The ECHR, which was indeed involved in the Abu Qatada case and some (but not all) of the cases about prisoners being allowed to vote, is not part of the EU.
Its job is to uphold the European Convention on Human Rights, which was drawn up after World War Two, partly thanks to Winston Churchill. The Convention is incorporated into UK law by the Human Rights Act (HRA).
The other court is the ECJ, which is an EU institution. Its job is to uphold EU law, including the right of free movement, and so it can rule on deportations.
of course the SNP have a plan because they are single mindedly for Scotland - NS is an unlikeable politician intent on destroying the United Kingdom for her own personal glory. She is not an MP thank goodness.
If the UK were to leave the EU, it would no longer be bound by rulings from the ECJ, but it would still be bound by the ECHR, unless it decided to leave that as well. - very important to distinguish between the two.