Board Thread:Online Discussion/@comment-50.8.113.94-20140610204913/@comment-92.202.103.152-20150331145113

Getting Tullius' coat is a quest stage omitted from the regular questline (cf. uesp). It only seems to play a role when you go see Jorn after killing Tullius (and not having left Solitude in between). That was what happened in my case, anyway.

Leave Solitude (I don't know how far one needs to go - I fast travelled to Whiterun and that did the trick) and come back. War state should be over and Jorn should talk to you just fine.