Thirteen Labour MPs have backed a Liberal Democrat bill requiring the government to begin negotiations on joining a bespoke customs union with the EU.
Labour's manifesto ruled out re-joining the existing EU custom union and Prime Minister Sir Keir Starmer has recently said such a move was "not currently our policy".
The vote on the bill was tied, with 100 MPs voting each way leaving Deputy Speaker Caroline Nokes to cast the deciding vote. She told MPs she would back the bill "in order to allow for further debate".
Although the bill has progressed, it is highly unlikely to become law unless it receives government support.