What did Donald Trump do today?

He was ordered by a federal judge to report for a deposition in early January.

In this case, the deposition relates to an ongoing legal dispute between Trump and celebrity chef Jose Andres, who are suing each other over a contractual matter that arose when Trump made derogatory statements against Mexicans on the campaign trail. 

Presidents can be sued for personal matters unrelated to their office, and can be compelled to testify during their term. For example, Bill Clinton was deposed in a civil suit while president, and this ultimately formed the basis of perjury charges against him in his impeachment trial.

Trump has been party to approximately 4,000 lawsuits, at least 75 of which are ongoing and may require his testimony. More are certain to follow--including by government agencies that will report to him--if Trump continues to refuse to divest himself of his business holdings.

Why is this a problem?

• It is bad if personal legal problems distract the president from his full-time job.

• A president who is an easy target for lawsuits can be manipulated.