"Free Vote"

When a bill is being voted on and the leader of the party says you don't have to vote with the party's official view (free vote). This implies that usually you vote with your party (unsurprisingly) but what's to stop you from not voting with your party on all occasions?

>>3
>implying the founding fathers expected politicians to be honest
To quote Hayek "you don't change things by getting good people to do the right thing, you change things by changing the political environment so that when bad people find positions of power they have to do the right thing".