You have to enforce the law

Charles Krauthammer asks the fundamental question about immigration.

On Arizona Governor Jan Brewer wanting first to secure the border and President Obama wanting first comprehensive immigration reform:

There is something very odd about this. The executive is required under the constitution to execute the laws. We have laws about immigration. The government, by its own acknowledgment, has failed 10 million times to enforce it. (Since there are that many illegals in the United States.)

And now it says: We'll only enforce it if we get comprehensive reform, i.e., we are not going to enforce existing law until we get a change in the law or new law.

[But] you can't hold an existing law hostage — [hold up] enforcement of it — to a legislative agenda you have. You have to enforce the law.

I do not understand how they can say this with a straight face in a constitutional democracy. You have to enforce the law