A friend is preganent by a guy that has an expired visa and she married him so he can stay in the US. Isn't there a new law that the marriage doesn't count? Can't he still b deported back to Jamaica ?

No the marriage does count ( they are married) but he can still be deported. They will be married but he will just be in his country so if they want to be together she may have to move there.

He can of course apply to immigration for the correct visa and he may or may not have to return to his country first.

But they will be married, but it does not keep him here