A robust legal system is not one where teams of lawyers make millions fighting for the rights of illegal non-citizens at taxpayer expense. If the illegals cannot fund their case they should get no aid, just like we'd get no aid if we arrived in any other country illegally (we'd get aid to enter our prison cell but that's about it). In fact, forget that, most UK citizens wouldn't get legal aid in our own country.
Everyone is equal before the law.

