Although the European Union (Referendum) Bill easily cleared its first hurdle, that was the easy part.
It will now be considered by a committee of MPs, giving Labour opponents a chance to sabotage it during a game of parliamentary cat and mouse.
Labour is expected to table lots of amendments. Crucially, it is a backbench rather than government measure because the Liberal Democrats do not want to enshrine a referendum in law. So it will have a limited amount of parliamentary time.
Opponents will have another chance to talk out the Bill when it reaches its report stage in the autumn. Even if it survived that and won a third reading, it would be unlikely to secure the approval of the House of Lords, where again time would be limited.
In the unlikely event that it becomes law, that would still not guarantee a 2017 referendum. No parliament can bind its successor and a Labour Government, or Lib-Lab coalition, could overturn it. Politically, however, it would be difficult to deny the public a say.