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.
Can a jagged maw player use the reaction loose 5 honor to negate a political action from severed from the emperor?
"Reaction: Any number of times per turn, after an action with a base cost of discarding the Favor targets one of your cards: Lose 5 Honor. Negate the action's effects."
I would think they could since the lose 5 honor is not inside of the :: and there isn't a cost?
Can a jagged maw player use the reaction loose 5 honor to negate a political action from severed from the emperor?
Yes. Thus it has been for, oh, 11 years. (Though it was admittedly Yogo Junzo's Army back then.)