This option was created to allow beings to apply for permanent residency and other rights without sundering all of their ties to their homeworlds. Dual citizens could live and work anywhere in the Federation, apply for Federation grants, and even vote in Federation elections. However, dual citizens owed allegiance to and were subject to the laws of both political entities of which they are citizens. Also, the homeworld of an applicant must allow dual citizenship as well. Cardassia Prime’s Detapa Council quickly passed a law allowing Cardassians to become dual citizens of the Federation, and Grand Nagus Rom bullied a measure through the Ferengi Economic Congress of Advisors that allowed Ferengi to take part in the program after purchasing a citizenship license. Dozens of unaffiliated worlds moved to allow this option to their citizens as well, but on Qo’noS, the High Council refused to follow suit. See 24th Century - Official Star Trek Online Wiki.