Terms of Endearment

Scully:  Mulder, we are supposed to be doing background checks not chasing X-Files. Mulder:  Scully, Spender just round filed this case-- it's unconscionable. Scully:  And what do you call rooting through his trash? Mulder:  Like that's any different from the assignment we're stuck with. Scully:  "We," Mulder?  I'm stuck with it.  You're not here.

That's Mulder, ditching Scully to chase after an X-File he's not supposed to be looking into and expecting Scully to cover for him.

General Punkesque Behavior

Dumpster Diving:  Ewww!  It's the only way Mulder could have gotten that case.  It must have taken quite some time for him to piece it together the shredded document.  Time he was supposed to be using working on the background checks.

Ditching Scully:  He had her waiting 45 minutes for his sorry ass as well.  He could have called her to let her know he wasn't coming.

Dragging Scully into the illicit X-File by trying to get her to examine sonograms related to the case.

Hate like the devil huh Mulder?  One can call Mulder a lot of things but subtle is not one of them.

Keeping Scully waiting:  That's not a very wise thing to do to one's partner.  Especially one who's risking her own ass to help.

Unprofessional Behavior

Going AWOL:  Naturally he will need Scully to help cover up his unauthorized absence

Criminal Activity

Stalking:  When you stake out someone and you are not assigned to the case it's called stalking and it's illegal.

Speeding:  I don't think that getting involved in a high speed chase during a case he's not supposed to be investigating is wise.