( CNN) Only person or persons at the Justice Department has the ability to stop special counseling Robert Mueller's Russia investigation. But what happens if that person is fired?

What Trump does next could trigger any number of messy legal combats. Here's what to know.

1. There is a succession plan

Solicitor General Noel Francisco The deputy us attorney general for the Office of Legal Counsel, Steven Engel The deputy attorney general for national security, John Demers The US attorney for the Eastern District of North Carolina, Robert Higdon The US attorney for the Northern District of Texas, Erin Nealy Cox

Bernstein: We're in a constitutional crisis

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