(CNN) Tensions are high on Capitol Hill after Attorney General William Barr declined to appear at a House hearing over the Mueller report.

If things continue to escalate, and Barr continues to resist Democrats' demands about the Mueller report, the country's top law enforcement officer could be found in contempt of Congress.

Here's what that means, and what could happen next:

What is contempt of Congress?

It means someone has obstructed the work of either Congress or a congressional committee.