Truce Zone: About as rare as the Neutral Zone, its counterpart trope, in the large, but mention should be given to both the Free Eilish Confederacy on the one hand, which occupies the majority of the Eilish Expanse constellation and whose policies of firm neutrality and not-terribly-restrictive legal system make it both a place where almost everybody is welcome and one of the favorite places for galactic intelligence agencies to play their away games (like, as it were, Casablanca IN SPACE), and on the other, to the red market which occupies most of the approximately-habitable planet Nepscia (Galith Waste), which welcomes anyone with money and guns.
(Well, technically it welcomes people with money and no guns even more, but they rarely find the welcome enjoyable. Shortly after which they rarely find anything, anything, any more.)