my boyfriend opened a credit card in another persons name from his home in mahoning couty ohio and then used that credit card in trumbull county ohio and was charged with taking the identity of another in trumbull county is that legal
I used to live in Hubbard, OH (a suburb of Youngstown).
If you are asking whether the prosecutor did a lawful thing by charging your boyfriend with identity theft, the answer likely is "yes". Most prosecutors do not intentionally file charges against someone if the prosecutors know that filing the charges is unlawful. Not all charges filed by prosecutors will become convictions.
If you are asking whether using another person's identity to open up a credit card account without permission of that person is unlawful, the answer likely is yes. Besides likely being a state crime, filing a false credit application with certain financial institutions may be a federal crime.
What your boyfriend should do is review his facts with an attorney.
If your boyfriend is indigent, he can ask for a public defender to be appointed as his attorney.
Your boyfriend should not discuss the details of his case with anyone, especially the police, except on the advice of his attorney. Except for persons able to assert some recognized privilege (such as attorney, religious adviser, spouse), anyone with whom your boyfriend discusses the details can become a witness against your boyfriend.