The bigamous marriage, while illicit, was not invalid.
Breaking social norms.
Origin of illicit
From Frenchillicite, from Latinillicitus, from in- 'not' + licet (“it is allowed”)
As a port it was notorious for its smuggling and illicit trade.
An important consequence of thus giving the study of primitive religion the wide scope of a comparative hierology is that magic is no longer divorced from religion, since the sacred will now be found to be coextensive with the magicoreligious, that largely undifferentiated plasm out of which religion and magic slowly take separate shape as society comes more and more to contrast legitimate with illicit modes of dealing with the sacred.
When the source of the name was forgotten its meaning was not unnaturally misinterpreted, and gained for Gawain the reputation of a facile morality, which was exaggerated by the pious compilers of the later Grail romances into persistent and aggravated wrong-doing; at the same time it is to be noted that Gawain is never like Tristan and Lancelot, the hero of an illicit connexion maintained under circumstances of falsehood and treachery.
In the 18th century land grants and illicit trade led to serious disturbances.
But now that the grandi were suppressed politically, the lowest classes came into prominence, "adventurers without sense or virtue and of no authority for the most part, who had usurped public offices by illicit and dishonest practices" (Matteo Villani, iv.