Pro-Leave MP Dr Liam Fox has raised questions over the legality of the agreement that Prime Minister David Cameron came to with European leaders in Brussels in February.
Speaking to the foreign affairs select committee Fox said that the UK is being asked to determine its relationship with the EU on the basis that "we have a watertight legal agreement, and clearly the democratically elected European Parliament doesn't agree".
His comments come after Alexander Graf Lambsdorff, vice-president of the European Parliament, said that Cameron's negotiation is nothing more than a deal "hammered out down the local bazaar".
Fox said that it's a statement of fact that the European Parliament could vote down elements of the agreement made by European leaders.
Back in February the president of the European Parliament Martin Schulz said he could not guarantee that MEPs would agree to Cameron's reform package.
Schulz' statement meant that the UK may not get the deal agreed by Cameron if it ultimately votes to stay in the EU. However, he did add that the parliament did not have a veto.
Back then Cameron said the deal will give "special status" to the UK in the EU.
And in that same month Michael Gove also claimed that the deal could be overruled by the European court of Justice.