A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 27 July 2007
I tried searching for this but couldn't find anything.
I understand that if you control Hida Sozen that he will not die if his chi reaches 0 due to another player's card effect. However, what if another player has given him a permanent chi penalty that will put him at 0 chi and then he gets another -1chi from one of your own card effects?
Does he die because the new penalty would reduce his chi below 1, or is he kept alive because he was already at 0 because of another player and values can't go below 0?
Martin Lund (rules official), 27 July 2007
EXCEPTION 2: A Personality’s destruction for having 0 Chi comes from the effect that last gave the Personality a Chi penalty, or from the rulebook if there was no such effect.
If you introduce a new Chi Penalty effect, that Chi Penalty is now considered to be the source of destruction due to 0 Chi - even if the Chi Penalty effect didn't actually cause the final value of the Chi stat to drop any further due to minimum of 0 rule.
Minimums do not prevent effects from being applied, but rather cause you to treat the final value of the card in question as the minimum value when the value would otherwise be less than the minimum.
To get a stat's current value at any given time, do steps A through C, below:
A: Apply all current bonuses and penalties.
B: If the total is below 0, treat it as 0. (Does not apply to Family Honor, Honor Requirements, and stats with a + or – sign such as an Item’s Force and Chi stats.)
C: If the total is less than a minimum or more than a maximum, treat it as the minimum or maximum.
For more information about card stats, you can take a look at this section.