Saints running back Mark Ingram will fight his four-game suspension, according to a press release from his agents. Ingram, it seems, will argue against the validity of the test results. 
“At the end of the 2017 season, as a result of a NFL mandated random drug test, Mark Ingram tested positive for a substance that was not a performance enhancing substance, nor an illegal substance, but a substance in fact permissible with the proper use exemption with the NFL,” the statement reads. “He has vigorously challenged the test results through the arbitration process. The arbitrator’s opinion is due on or before Wednesday, May 16. Upon having the opportunity to review the arbitrator’s opinion, we will explore what further options are needed.”
Ingram’s reps also note that the substance in question is permitted to be used by players with a thereputic use exemption, but it doesn’t seem that Ingram had a TUE for whatever it was. The real crux of their case will come down to their challenge of the test results. In the past, players have questioned the handling of samples as well as the methods for testing.
For now, Ingram is scheduled to miss games against the Buccaneers and Browns and road contests against the Falcons and Giants. If the ruling stands, he will not play until Week 5 against the Redskins.