Yes, under Section 75 of the Constitution, the High Court has the power to make decisions based on international treaties we've signed. They've decided that they can do this no matter what Acts of Parliament decide and as there's no appeal of their decisions, they can overrule Parliament.
It would appear to be a huge industry and so complicated only a team of frightfully expensive lawyers could guide one through the maze of obligations to various treaties. Meanwhile, our sovereignty has been eroded if not extinguished.
The terms illegal alien, refugee and migrant have become blurred. Deliberately imo.