There are already immigration courts. The problem is that there are only ~250 immigration judges, total. So, even if the number of illegals is at the low end of the estimate (11 million), that would be 48,000 deportations per judge. Even if 75% of illegals self-deported, that's still 12,000 cases per judge. Given the complexity of the immigration laws, it would take a long, long time to clear that kind of backlog.
It's not an insurmountable problem (more immigration judges could be hired - though that brings with it its own set of problems), but it is a problem that should be taken into account.
Exactly my point. Hire more temporary judges and get the illegals their due process.