The San Francisco 49ers linebacker Aldon Smith has been suspended for nine games by the NFL. A statement on Friday from the league said Smith had violated the NFL’s substance abuse and personal conduct policies.

He will not be eligible to return until 10 November, the day after the 49ers’ game against the New Orleans Saints.

Smith’s nine-game ban came a day after NFL commissioner Roger Goodell announced changes to the league’s much-criticised policy on players found guilty of domestic violence, increasing bans to between six games and a lifetime.

A two-game ban given to Baltimore Ravens running back Ray Rice, who did not contest a charge of aggravated assault against his then fiancée, prompted widespread criticism of the league this summer. This week, the Cleveland Browns wide receiver Josh Gordon was banned for the full 2014 season, for using marijuana.

“Our organisation has known this decision would come and we have prepared for it as a team,” 49ers general manager Trent Baalke said in a statement. “Aldon has taken responsibility for his actions and has continued to show growth personally and professionally. We will continue to support him, but it is time to put this matter behind us and focus on the season ahead.”

Smith, 24 and one of the NFL’s top pass rushers, missed five games last season to undergo treatment at an in-patient facility following a DUI arrest on 20 September. Just before training camp began last month, he was sentenced to serve three years of probation and to spend 11 days with a work crew after he pleaded no contest to drunken driving and weapons charges.

He has repeatedly said he has been sober since his DUI arrest. Smith played in a 27-7 home loss to the Indianapolis Colts on 22 September, two days after he was arrested and jailed on suspicion of DUI and marijuana possession. After the game, he publicly apologised for his behaviour and later announced he would leave for treatment.

While the 49ers went on a five-game winning streak without him, Smith’s menacing presence was sorely missed. The team still picked up his 2015 contract option this spring.

In his latest run-in with the law, Smith was arrested on 13 April at Los Angeles International Airport. Police said Smith was randomly selected for a secondary screening and became unco-operative, telling a TSA agent he had a bomb. No charges were filed.

In November, he pleaded not guilty to three felony counts of illegal possession of an assault weapon, stemming from a June 2012 party at his home. Investigators said several shots were fired, two partygoers were injured and Smith was stabbed. In the subsequent investigation, prosecutors say detectives found five unregistered and illegal weapons in Smith’s house.

Last season, Smith finished with eight and a half sacks and 34 tackles in 11 games with eight starts. He was initially worked back in slowly, but demonstrated he had stayed in shape while away.

Selected seventh in the 2011 draft out of Missouri, Smith had a franchise-record 19 and a half sacks during the 2012 season, in which the 49ers lost to Baltimore in the Super Bowl.