Legal Question in Immigration Law in Ohio

I'm not sure what your concerns are as a minister? His immigration status is not relevant so far as their ability to marry. If they've been together in a relationship approximating marriage for 7 years, it would seem that it is a marriage in practice, just not by name or law. Thus, it should meet the standards of a marriage within your faith and within the eyes of the law. Being lawfully married does provide him with immigration benefits, but they will be required to prove that not only are they married, but that is is also a valid marriage before immigration will approve it.

I echo what Attorney Brandabur has stated. So long as they're eligible under the laws of Ohio and your local jurisdiction (having a marriage license), there is no issue with you performing the ceremony. As for the bona fide nature of their relationship (not just the legality), that is up to their immigration lawyer to prove to USCIS.