I have a confession to make.
I'm really bad at remembering rules.
Despite playing D&D for nearly 40 years, and despite getting into Warhammer in the late 1980s, I rely on other people much of the time if it means avoiding flipping through books at the table (or searching on my tablet).
In that regard, I kind of like when someone at the table is a rules expert. Bring on that font of knowledge!
But rules lawyers are a different breed.
What's so bad about rules lawyers?
Rules lawyers or any kind of jerk at your table prioritize something other than the fun of the people they are with.
Be that maxing out their characters using loopholes and quirks of the system, or demanding everyone follow their interpretation of the rules.
Rather than making the game better, they are sacrificing the game at the altar of BEING RIGHT.
Why this can happen innocently
Having grown up and spent my career with nerds and engineers, and being neuro-flavored myself, I know how to spot someone who is acting with different programming than the default.
The need for things to be just-so can be stronger than our need for acceptance. Sometimes it is not what is said but how.
This means people who say "boot them from the game" or worse might need to take a breath first before acting.
Why this can happen maliciously
Sometimes a jerk is being a jerk because they are a jerk.
But what is the motivation there?
- Ego - Hey look at me and how awesome I am.
- Competitive - They might want to win at all costs, or it might be they want to bring the others down a peg or two because they seem them having more spotlight or status.
- Division - Could they be wanting to split the social group?
- Chaos - Griefers, people who want to spoil other's fun, exist in all communities
- Yucking Yum - Maybe they don't want to play that game, or they prefer a different style of play, and if they can't change things democratically, they are going to force your hand?
Spotting meta gamers
You will know a meta gamer rather than a rules lawyer because they will only raise rules when it benefits them or hurts a competitor.
My father-in-law is very lenient about games when it is his own mistake but he will wade through fine print if someone else is getting ahead.
What to do?
First, this is a good reason to have a session zero where you explain your house rules and any expected behavior.
After that, I always say what my dad taught me about leadership; criticize in private, praise in public.
Take the person to one side and listen, then act.
How do THEY feel the situation went?
What is their thinking?
Get them to walk you through things.
Confrontation doesn't work
Games are about having fun with nice people.
Conflict reduces the fun and ultimately the number of people who want to spend time with you.
First person to get angry, loses.
Remember to take a pause before reacting, and remind yourself and everyone else why you are at the table.
Ultimately there are rules but also your table is your table
Playing a game with a ruleset implies that you want to follow those rules but if your table or GM decides that things are better a certain way that is ok too.
Remember very, very few people play Monopoly based on the actual rules as written rather they play how they were taught ... by people who hadn't actually read the rules.
Most RPGs actually explicitly state that their rules are guidelines and for you to use the rule of cool, and even wargames outside of a tournament can be as lenient as you like!