The Minnesota Vikings are speaking to candidates for their currently filled defensive coordinator position and have notified the Jacksonville Jaguars they will interview Mel Tucker. Tucker has been the Jaguars defensive coordinator, at least in title, since the 2009 season. In the 2011 season, Tucker served as the Jaguars interim head coach after Jack Del Rio was fired. With Tucker as the interim head coach, the Jaguars went 2-3 in their final five games.
You'll notice the Vikings simply notified the Jaguars of their intent rather than asking permission because they don't have to. Tania Ganguli of the Florida Times-Union explains why:
Tucker isn't one of the coaches disputing the end date of his contract. His contract expires at the end of January. According to NFL tampering rules, as of today at 12:01 a.m., the Jaguars no longer have exclusivity on coaches whose contracts expire this offseason. That expires on the second Tuesday after the team's last game.