ST. JOSEPH, Mo. Demarcus Dobbs, who will serve as Justin Smith's primary backup this season at right defensive end, will miss the 49ers' first game of the season after violating the league's policy on substance abuse.
Dobbs was arrested last season for marijuana possession after he was involved in a single-car accident near the 49ers' training facility in Santa Clara.
He will be eligible to return to the active roster Sept. 9, one day after the season opener against Green Bay. He remains eligible to participate in all offseason and preseason practices and games.
A statement from general manager Trent Baalke said: "The San Francisco 49ers organization supports the NFL's code of conduct policy and their recent decision regarding Demarcus."
Dobbs was arrested for marijuana possession and suspicion of DUI in November after crashing his car on the San Tomas Expressway in Santa Clara. He was not injured, and no one else was in the car. Dobbs did not make the trip that week to St. Louis.
While Dobbs has been Smith's primary backup this offseason, other players like Will Tukuafu, Ian Williams and Glenn Dorsey could step in at the position this year. Tony Jerod-Eddie and Lawrence Okoye likely will play there Friday against Kansas City.