Texas wants to arrest immigrants in the country illegally. Why would that be such a major shift?

Washington: Immigration laws are federal laws not state laws and enforcement of immigration law is the domain of federal law enforcement. Homela...

Washington: Immigration laws are federal laws -- not state laws -- and enforcement of immigration law is the domain of federal law enforcement. Homeland Security agents and officers are responsible for arresting migrants who are caught crossing the U.S. border illegally, whether from Mexico or Canada.

They're also responsible for arresting and deporting people who are in the country illegally. That's why the news in Texas over immigration enforcement is so unusual.

Lawmakers there passed a bill that would make illegally crossing the border a state crime, which would theoretically allow state law enforcement to arrest migrants.

But that clashes with how, generally, laws work in the U.S. The Texas law was supposed to go into effect this month, but there's been a big back-and-forth in the courts about that.

Here's a closer look: