House Judiciary Committee Says It Needs Don McGahn To Testify

The House committee is seeking testimony from Don McGahn as part of its investigation into potential obstruction of justice by President Trump during the Mueller Russia probe. The committee believes McGahn's testimony could influence impeachment decisions. The Justice Department argues for case dismissal, citing the House's prior impeachment vote. The House also seeks Mueller's grand jury materials to assess if Trump lied. The DC Circuit Court will hear both cases on January 3rd.

How might the documents related to Mueller's grand jury materials impact the House's investigation?

What is the significance of the DC Circuit Court of Appeals hearing both cases?