Fmr. top tax official: Trump lawyer threat on tax returns 'didn't really say anything'

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George Yin, the former chief of staff of the Joint Committee on Taxation, tells Lawrence that it is "absolutely" the responsibility of Congress to obtain a president's tax returns to ensure that the letter of law is being followed by both the president and the institutions overseeing a president's tax returns. Lawrence O'Donnell is also joined by Ways and Means member Jimmy Gomez.