We're screening airline passengers based on their country of origin now. A common sense solution that's been a long time coming. We're screening them because there is a high probability that if someone is going to blow up an airliner, they will be from one of these countries.
This can be applied pretty much directly to the problem of illegal immigration. You don't have to have a PhD to realize that the majority of illegals around the southern border of the U.S. are from Mexico. They have broken the law to come here and as such we have the right to discern who they are and deal with them in an appropriate manner. You can call it profiling, you can it whatever you want, but it's mirroring a policy put in place by this administration to deal with terrorists.
If I was arguing this before the SCOTUS, I would be bringing up these policies.