A "Two ships have been destroyed! Objective complete."
B "No, two ships were just destroyed at once, but with the one that died earlier that makes three. Your objective says 'two ships destroyed' not 'two or more ships destroyed'"C "While that's true, the situation in which three ships have been destroyed does not preclude two ships also having been destroyed. 'Three ships have been destroyed' and 'Two ship have been destroyed' are both true statements in this situation."
A "In that case it's valid to say that two ships have been destroyed three times, 1&2, 2&3 and 1&3."
B "So you win then, first to three objectives."
C "Nah, the plural in 'objectives' means that you can't just complete the same objective three times."
A "But I can do this one twice and one of the others once and that'd be okay?"
B "Maybe, but you've not done this one twice, you've done it three times."
I've started to let playtesters loose on the rules for Space, Monkeys and Cannibalism. The process makes me think of piranhas. I've never seen piranhas eat a live animal, I felt compelled to look for a video on the subject, if anything it's more similar to how poorly worded rules documents are attacked than I'd imagined. The main difference is that in the case of the rules it's a good and useful process and I'm glad to be going through it. I'll share the results with you once I'm done, for now, it made today seem like a good day to talk about rules lawyers.
Having heard the topic discussed, both in person and online, it's abundantly clear that nobody knows what a rules lawyer is or whether you want one. For some people a rules lawyer is someone who's trying to twist the rules to their purpose, creates long arguments and generally spoils the game. For others it's someone who makes sure that there's a level playing field in which everyone is playing by the same rules, fairly resolving problems in an effective manner and a generally helpful chap. I'd say that people who believe in these two definitions have both accused each other of using the term improperly, but that would imply that there are only two definitions with supporting groups doing that. The rules lawyer is, apparently, a master of disguise.
Rather than trying to define "Rules Lawyer" I think it will be more productive to look at the different ways in which individuals engage with rules. All of the things that I'm about to discuss have been called "rules lawyering" by one group or another, but the important thing from a design point of view is to understand how players might interact with your game rather than to be certain which names to call them for it.
Players rarely have perfect command of the rules in a given game, especially if it is someone's first game or if it's been a long time since they last played. The timing with which rules are remembered and brought up can have a big impact on the game.
In Settlers of Catan when a seven is rolled any player with seven or more cards must discard half of their hand. Some players might be inclined not to mention this if they have more than seven cards and everyone else appears to have forgotten. Others might notice that a new player is about to end turn with eight cards in hand and offer a rules reminder in case they have forgotten. Oddly the rules lawyer label can also follow doing nothing, as a lot of players are inclined to identify "Noticing that a new player has forgotten a rule and not mentioning it until after they can't do anything about it" as an action in of itself.
Sometimes the language used for a rule makes it difficult to interpret what the rule is telling the players to do. People vary a lot in how able they are to parse complex sentence structure and so it's not unusual for one or two players to be more involved in interpreting exactly what is meant by a given sentence. The sort of discussion I wrote about in the introduction to this post is an example of that, where the precise English meaning of 'Two ships have been destroyed' is being debated. There's sort of an example within an example in that I felt the need to write that they had been destroyed simultaneously as the alternative would leave some readers thinking "Why doesn't player A just claim the objective after the destruction of the second ship but before the destruction of the third ship."
There are also issues of how to interpret proscriptive rules. In general rules are written to be a list of things that you can do or that can happen and the default assumption is that anything outside of these rules cannot happen. Players will engage in interpreting the absence of wording as much as they engage with interpreting the wording of rules. For instance the rules for Chess need not state that you cannot win by knocking over your opponent's king and declaring them to have resigned. They state how a player might resign; it can be assumed that all other methods are illegal.
Inevitably the rules initially printed for most games end up flawed and require updating. To continue with Chess as an example, a rules patch was introduced in 1972 after this famous chess puzzle (white to mate in three moves) showed a rules exploit:
The solution is for the white pawn at e6 to advance to e7, the black king must move to d3 or f3. The pawn then advances to e8 and promotes to a rook. This means that wherever the black king went it still only has one legal move c2 or g2. At this point the white king castles with the newly created rook causing the checkmate. As the rules specified that a king and rook that had not move could castle, but did not prohibit castling if the rook was newly created from a piece that had moved it was a legal move. The rules have since been amended to require that castling pieces be on the same rank (row).
The relevance of this to how gamers deal with the rules is in how proactive they are about obtaining and enforcing such errata. Most games are playable and enjoyable without rules corrections so some gaming groups will never even look at corrections on the designer's website. Others want the intended experience and will add print outs of corrections to their rulebook and insist that they're used at all times. These decisions interact with the other rules, especially if there is disagreement on whether a game is being played with the original or corrected rules after the game has begun.
RAI vs. RAW
The role of RAI (rules as intended) vs. RAW (rules as written) can hugely affect the way a game plays. Some players will do their best to follow the intention or spirit of the rules while others seek to execute the instructions in the rules exactly. In theory RAW leads to fewer arguments as it's much less ambiguous and leads to there being obtainable correct answers to any questions, in general it is favoured for tournament and competition play. On the other hand RAI will produce a game experience more similar to the designer's intent, which is likely to be what was tested and overall produce a better more enjoyable game. Few players always insist on RAI and few always insist on RAW, most find a balance between the two that is palatable for them.
I think one of my favorite examples of this is the 3.0 dungeons and dragons rules on drowning. Once a character starts drowning (which can be some considerable time after being immersed in water) they are unconscious, next round they are dying and on the following round they are dead. Rules as written, there is no way to stop the drowning process once it has started. Almost everyone will agree that the RAI is that should the character be removed from the water they will stop drowning, but by the RAW this does not happen.
This sort of problem is perhaps more common in RPGs than boardgames, as they have a much larger scope. However it is not uncommon for boardgame designers to rely on players to follow the spirit of the rules as printing exhaustive rules is expensive and can act as a barrier to entry for new players.
On a side note, some groups I play with also use RAE, or rules as explained. Essentially if we have new players, we play by whatever rules were explained to the new players at the start of the game. In the event that it's later discovered that the explanation contradicts the rules then we play by the explanation, since that's what all of the new players have been moving and strategising around. If an explanation for new players was lacking it should be the people who gave that explanation who have their game fall apart for it, rather than the other way around.
The Rules Lawyer
For some, the rules lawyer is a figure who remembers rules when it benefits them, twists the exact wording of rules to apply a RAW that's far from the RAI and pulls in extra rules from errata as and when it suits them. Others define the rules lawyer as someone who fairly interprets the exact wording of the rules to determine what the RAW says and then carefully balances that with the RAI to make a reasonable determination - or anything in between. I'm just going to think of players as people who bring up rules at the start or when it suits them, people who favour RAI or RAW, people who can be bothered downloading and printing errata or not. This approach paints a more complex picture, but I also think it's more complete.
From a designers point of view it's worth remembering that these different types of players all exist and to think about how your game will function for each of them. None of them are fundamentally wrong (well, maybe people who don't apply rules to themselves if nobody else remembers) and there are different ways to write a game so that they'll get the most out of it. Probably the biggest challenge is constructing a game such that players who engage with rules in different ways could still enjoy playing the game with each other.