As dozens of players have found out over the past few years, it's almost impossible to get an NFL suspension overturned, especially if that suspension is for violating the league's policy on performance-enhancing substances. However, that's exactly what Julian Edelman is going to try to do this week and he's got a plan of attack to win his case. 

According to ESPN.com, Edelman will be appealing his four-game suspension on Monday and the Patriots receiver plans to focus on two key points during his case. The first issue that could help Edelman is that the receiver tested positive for a unknown substance. As MMQB.com reported on June 11, the NFL had to have scientists analyze the substance because the league's drug testers didn't recognize it. 

The odd test result is a big reason why Edelman sent out a peculiar apology on Instagram shortly after his four-game suspension was announced on June 7

"I don't know what happened," Edelman wrote. "I've taken many, many tests obviously over the course of my career, and nothing like this has ever happened."

The other issue Edelman will use to try and win his case revolves around chain of custody. According to ESPN.com, Edelman's team believes there was a "mishandling of the documentation and delivery" of the receiver's test results. Apparently, the league made multiple errors when handling Edelman's tests. 

If Edelman can prove that happened, he might be able to get his suspension overturned. Back in 2012, Richard Sherman got a four-game suspension overturned after he proved that the NFL made several errors regarding the chain of custody of his urine sample. 

To help plead his case, Edelman has hired an outside lawyer in the form of Alex Spiro, according to ESPN.com. Spiro has been known as a go-to lawyer for multiple NBA players who have faced legal trouble over the past few years. 

If Edelman gets his suspension overturned, that means he'll be on the field for the first four games of the season, which will come against the Texans, Jaguars (away), Lions (away) and Dolphins. Obviously, if Edelman loses his appeal, then he'll miss all four games. 

No matter what happens, Edelman will be eligible to participate in practice during all of training camp and he'll also be allowed to play in each of the Patriots' four preseason games. If the receiver does get suspended, the ban wouldn't start until after New England's final preseason game on Aug. 30.