A note on some stuff that is coming for combat.

[nas1m]

How about more limited things that are AWESOME but have out of combat results?

"The use of antimatter-based weapons in combat has horrified the non-aligned races, leading to the formation of an Anti-Federation Popular Movement on Several Planets."

Now that is a good one... Kudos !

[JAlfredGoodwin]

That's a really good idea!  Because yeah, being able to win one impossible battle with ease by using a "cheaty" sort of weapon is no big deal if it causes major repercussions out in the solar system.  I love that!  Do you mind putting that in mantis so I don't forget?

Put it in Mantis.

There are other possibilities of course.  Cluster Bombs, Carpet Bombing, Land mines, etc.  Perhaps two or three races decide to outlaw precision munitions that bypass armor, and every time you get caught using them, you suffer a relationship hit of some kind.

Then, you could always be tried for War Crimes in Absentia by some race, and now you constantly have to dodge their police, and lose access to their pilots\ships...

[x4000]

Thank you!

And yep, having to dodge their police and not being able to use their pilots and even not being able to do things with them politically are all well in the realm of the sorts of things we already do.  We don't do that specific thing, but we do have:
- Races send assassins after you when they hate you enough (this could easily be adapted to police in your case).
- Races won't let you use their pilots until certain conditions are met, and if certain other conditions happen then your pilots will actually desert from your fleet, taking their ships with them!
- All sorts of things cause you to be unable to make certain kinds of political deals with various races, or to limit your options, or open up new options.

So what you're suggesting is both cool and something well within the existing scope.