Might some of the villains Clark (with Lois) has put behind bars attempt to find some legal loopholes around the fact that the person who dished the dirt on them wasn't who he said he was at the time? Said villains might try to bring various court cases against Clark or claim a mis-trial or simply an unsafe conviction and thus get released from jail.
BTW, I'm trying to think of stuff other than personal threats to Clark, his family and his friends, since that seemed to be what you were asking for.
Yvonne
