I think the intent is for the candidate to show that he/she has not been involved in illegal/suspicious activity. Back in the 70's a sitting VP had to leave of

I think the intent is for the candidate to show that he/she has not been involved in illegal/suspicious activity. Back in the 70's a sitting VP had to leave office due to charges of extortion, bribery, and others (see Wikipedia on Spiro Agnew). It was Mitt's father, George, who began the voluntary practice of disclosing tax records.