The Simpsons did it first

Oh no! The USA meddling with foreign goverments because bananas? Unconceivable!

They are arresting people. They need to investigate if those people are immigrant, then investigate if they are there under an irregular status, then they have to investigate in order to find out if any crime has been commited.

People is not illegal. Those arrests/detentions seem to be the illegal part.

…but we weren’t