I'd like to be able to toggle individual commodities to be "legal" or "illegal" (or if you prefer, "traded" versus "embargoed"). Want to starve out the Sector by only providing Food to your own faction? Embargo it, then raid everybody else's farms!
Of course, toggling every commodity to be illegal comes with consequences
TM. The more out-of-tune with another faction you are, the less they like you - say, a perfect match nets you +5/month in Attitude, while each differing legality is -5 to that. So, theoretically Hegemony and Luddic Church would have a permanent -5/month to each other because of their disagreement over trading two commodities.
In combination with my
tariff slider suggestion, this would obviate the utility of the "Free Port" button.