Illegal marriage can have implications for both parities. There may in fact be charges brought against individuals that take part in an illegal marriage. However, the implications vary base on the specif circumstances.
If for example, an individual took part in an illegal marriage to gain citizenship to a country, they could be charged with fraud. This type of marriage takes place simply for an individual to gain citizenship, in the absence of a real relationship between the couple. In that case, both individuals could face charges.
Illegal marriage may also take place for financial gain. For example, one spouse may believe the marriage to be legal, while the other is aware that it is not. If the spouse that is aware of the illegal marriage, took part in order to reap financial benefits from the other spouse, they could face additional fraud charges.