Von Miller ruling likely by season

The NFL is targeting mid-August as an appeal date for Denver Broncos linebacker Von Miller's four-game substance-abuse suspension, though it could be heard earlier, and a resolution to the case is expected before the regular season begins, a league source told ESPN NFL Insider Adam Schefter.

The NFL Players Association is working closely with Miller on his appeal. He addressed the looming suspension in a tweet Monday afternoon, proclaiming his innocence.

It is unknown which substances Miller is accused of using. Under NFL policy, Miller would have to test positive for banned substances twice before facing a four-game suspension.

The Denver Post reported Monday that Miller tested positive for amphetamines and marijuana in 2011, his rookie season.

Without Miller, the second overall pick in the 2011 draft, the Broncos defense would be missing its best pass-rusher for its first four games -- against the Baltimore Ravens and former Bronco Elvis Dumervil, who was released in the offseason after a deadline fax fiasco, the New York Giants, Oakland Raiders and Philadelphia Eagles.

If suspended, Miller would be able to participate in all of the workouts at training camp but would have to leave the team after its final preseason game on Aug. 29. His season debut would be in Week 5 when the Broncos visit the Dallas Cowboys.

Miller, 24, had 18.5 sacks last season for the Broncos, following a 2011 season in which he recorded 11.5 sacks and was named Associated Press Defensive Rookie of the Year. According to ESPN Stats & Information, since Miller entered the league in 2011, only Jared Allen (34), Aldon Smith (33.5) and DeMarcus Ware (31) have more sacks than Miller (30).

Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.