You're ready for a night of adventure and intrigue! You have your dice set out where you want them, your books and laptop are close to hand, and you have bookmarks on all the pages you'll need for reference. You have a case full of soda, and a buffet of snacks just waiting for your players. No matter how well-prepared you are, though, you know one of your players is going to raise objections. We'll call him Jim. Jim is a guy who knows this game like the back of his hand, and he can argue how the rules work better than anyone you've ever seen. The problem is that he's crossed that line from a player who knows the game, to a player who's become a rules lawyer. He's a good player, and you don't want to get rid of him, but you really wish there was a way to mitigate this tendency he has to clear his throat and correct anyone who does something against the rules.
Fear not, fellow Dungeon Master. I'm here to help. All you need to do in order to keep your rules lawyers from bringing down your game is to follow these simple steps.
Also, if you enjoy this piece of DM wisdom, you'll find more over at Improved Initiative.
Have A Pre-Game Talk
The best thing you can do to nip rules lawyer complaints in the bud is to sit down, before the game starts, and make sure you are familiar with the particular rules all your players are going to be using the most. For example, if you have one player whose character is totally focused on grappling, then you need to know how grappling rules work. If you have another character who is largely stealth based, then be sure you are familiar with all of the nuances that come with concealment, cover, and opposed checks. If you have someone playing a variant of a wizard who casts through psychic power, make sure you know how that works instead of just trusting the player to get it right.
This serves two functions. First, it gives you a tight grasp of what your party is capable of, and it ensures that you and your players are on the same page regarding how the mechanics of the game work. Having them explain their abilities to you ensures that you both agree on how those abilities function. Secondly, it lets you identify and correct any red flags before the action gets going. This prevents you from being in the middle of a tense situation, and needing to make rulings on the fly.
Rule Like a Judge
Even if you do all of your prep work, there will still be incidents where a rules lawyer may try to argue something. Most of the time this will happen in the midst of a busy situation, like combat, or when the rules may be unclear. In order to resolve these instances quickly, you need to institute the following format, and make sure all your players agree to it. If you'll notice, it's not dissimilar to how things work in a courtroom.
First, ask the player who raised an objection to read the relevant ability or rules section they're talking about. It is their job, as the person making the objection, to have the section ready to hand. This prevents players from misquoting a rule from memory, which saves a great deal of time and argument.
Second, allow the objecting player to make a case for his view of how an ability should work. Listen to the objection, and ask any questions you have as the DM, but keep it short, simple, and to the point.
Third, make a ruling. Once your ruling has been given, it is final for this session. If you need to, write it down so there's no confusion about what you said. The matter is not to be brought up again, and the game should be allowed to proceed with the ruling given.
All told, making a ruling with this three-step process should take no more than a few minutes. It will help keep the game on-track, and cutting off any further arguments or objections on the matter means that players making an objection need to make their case clearly, and accept the results you give them.
In-Depth Conversation and Research After The Session
Not all your rulings will be perfect, but if they haven't done any permanent damage to your game (ie. no one's character died because of your ruling) then you can look at any issue more in-depth later. If a player is still unhappy with the way a ruling was made (whether that player was your resident rules lawyer, or another player entirely), take some time between sessions to talk the rule over more in-depth. Ask about it on forums, and look for any clarification you may have missed. If it turns out you wish to change your ruling, or add nuance to it, then you should make that announcement to your table before your next session gets rolling.
Stay on Top of The Characters' Development
Keeping your rules lawyer defenses up isn't a once-and-done sort of thing; you have to refresh yourself in order to stay current throughout your game. That means whenever characters gain new abilities, special equipment, or other tools they can use in future encounters, you need to have another conversation with your players to ensure you're all on the same page again. If you do this long enough it will become reflex; part of the routine of leveling up, spending XP, or whatever mechanic your game uses for increasing a character's relative power.
Every Group Has Its Own Rhythm
If you've gamed with the same group for a while, chances are good that you already have a rhythm that works for you. You know your fellow players, and you've all established your own group policies. Maybe you encourage players to discuss strategy out of character, maybe you forbid it. Perhaps you want all character sheets a few days in advance when players have added abilities or gained a level so you can do a review, and maybe you trust your players to do that job on their own.
The method of resolving rule disputes and objections I've put forth here isn't a game requirement. It's just a suggestion. If you already have something in place that works for your group, then keep doing it. If you don't have something in place, or you want to try something different to see if this method works better, then go forth and play! The only real judge of how well a method works is how well your players like it, and if it helps your game. Hopefully that is what DMs and players alike will get out of this suggestion.