DM's Please read this

The DM is not there to railroad the players, nor can he control the minds of the PCs. Nobody can reach into your mind anytime, anywhere, and make you do something you did not choose to do of your own free will. I actually have seen almost every DM in the guild use NPC party members to steer the game, this is usually a bad practice and a crutch for those who cannot handle variation in the party's mindset. If the party needs to do something specific, the DM can use other factors in the world to show the party that it needs to be done, but it is truly up to the party whether or not it will be done by them. Yes, this means on rare occasions the DM's carefully laid plans will be altered by a party who does not follow your plans exactly, and it can lead to world altering effects sometimes. Unless the game starts off with all party members as a part of an army, with specific orders from a commanding officer, they have the right to say 'no'. If a DM has a party that doesn't like doing something, and that is what he planned for the game, maybe he should communicate more of his plans to the party up front when recruiting players. Also, if a DM does not understand the motivations and workings of the PCs enough to know that regardless of what he says they have a code of honor that requires them to behave a certain way, that is a failure to communicate in some way, maybe on the players, maybe on the DM or DMs, maybe on both. Any way you look at it, if you expect the PLAYERS to simply CONFORM, reread the Dungeon Master's Guide, and probably the DMG 2 would be a good idea too.