Neither the Redskins nor Trent Williams is offering further details about how the Pro Bowl left tackle ended up getting suspended for four games at the season’s midpoint, apart from the six-sentence statement the team issued within minutes of the announcement of his punishment Tuesday evening.

The development caught many by surprise, largely because under the NFL-NFLPA’s revised substance-abuse policy, issued in September of 2014, it takes four positive or “missed” tests (which are treated the same as positive tests) to trigger a four-game suspension when the drug in question is marijuana.

On Tuesday, the NFL announced that Williams was suspended those four games without pay for violating the policy. The suspension sidelines him for the 4-3-1 Redskins’ upcoming games against Minnesota, Green Bay, Dallas and Arizona. According to two sources with information about the situation, Williams triggered the penalty by missing a test.

How did he reach this point?

The 41-page policy serves as a road map, spelling out the schedule of penalties for failing (or missing) a drug test. The policy also spells out a time frame in which a player with a history of positive tests can have his record “cleared,” in effect, for proving he’s “clean” by passing random drug tests.

Williams did that, according to sources with knowledge of his situation. The positive marijuana tests that triggered a four-game suspension in 2011 didn’t count toward his current suspension, they said. Williams was believed to be starting from scratch.

Both the NFL and NFL Players Association agreed to the substance-abuse policy, which is administered by medical professionals jointly appointed by the NFLPA and NFL.

Another key distinction: The NFL and NFLPA relaxed the standard for what constitutes a positive marijuana test in its 2014 policy revisions. Prior to 2014, a level of 15 nanograms of THC (tetrahydrocannabinol) per milliliter of urine or blood was counted as a positive, the most stringent standard in pro sports. Under the revisions, 35 ng/ml counts as a positive. A nanogram is one-billionth of a gram.

Here is the NFL’s current schedule of penalties for marijuana positives. If it was applied correctly, it serves as a road map, in effect, for how Williams ended up with a four-game suspension:

1. First violation: Referral to a substance-abuse program.
2. Second violation: Fine equivalent to two game checks. (The player’s NFL team isn’t necessarily informed, as the punishment does not affect playing time).
3. Third violation: Fine equivalent to four game checks. (Again, the team isn’t necessarily informed).
4. Fourth violation: Four-game suspension.
5. Fifth violation: 10-game suspension.
6. Sixth violation: One-year banishment.

Many former NFL players and some health advocates argue that the policy’s stance on marijuana remains too harsh. They argue that marijuana is a safer, more effective pain-killer than many of the addictive drugs typically prescribed for pain. Others say marijuana helps them relax and speeds healing following the amped-up punishment of game day.

All NFL players are tested once each year during the offseason, between April 20 and Aug. 9.

Players who test positive are referred to a treatment program for 90 days and can be tested as frequently as deemed necessary for a proper evaluation (Stage One). A player who tests positive while in Stage One is referred to Stage Two and subject to frequent random tests, but no more than 10 times per month.

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