A Tongan Noble Representative, Lord Fakafanua, has joined forces with eight opposition MPs to defeat the Arms and Ammunition Amendment Bill.
The amendments would have cut the penalties for illegal possession of guns or ammunition.
Radio Tonga reports that a vote tied at nine apiece was resolved by the chairperson of the Committee of the Whole House, Siosifa Tu'utafaiva, opposing the amendment.
A similar measure was passed last year but vetoed by the late king, George Tupou the 5th.
Two nobles are facing charges under the current legislation.