The House Oversight and Investigations Committee hearing Monday into missing emails related to the IRS's scandal got heated after Democratic Rep. John Tierney accused Republican members of the committee of disrespecting IRS Commissioner John Koskinen.

"Mr. Koskinen, good evening and thank you for being here," Tierney said. "I don't think I have seen a display of this kind of disrespect in all the time I have been in Congress. It is unfortunate that anyone would be subjected to it."

Committee Chairman Darrell Issa then cut off Tierney "I would caution all members not to characterize the intent or the character of your fellow members here."

"But it's fair game to question the integrity of the witness," interjected Koskinen.

"The rules of the House speak to questioning the integrity of members," Issa added.