Monday was the first day of trial for Stephen Tanabe, a Contra Costa County, CA Sherriff's deputy who accused of arranging "dirty DUI arrests" for private investigator Christopher Butler.

Tanabe allegedly received cocaine and an expensive Glock gun from the private investigator in exchange for the DUI arrests, which were intended to strengthen the wives' positions in divorce and custody cases. Employees of Butler would allegedly entice the men to drink, and Tanabe would be waiting to make the DUI arrests. 

"To put it more bluntly, he sold his badge," Assistant U.S. Attorney Philip Kearney told the jury during his opening statement in federal court. "He violated his duty to provide honest services," the prosecutor charged.

The DUI operations were part of a wide-ranging police corruption scandal centered on Butler and former drug squad commander Norman Wielsch.

Both Butler, who is slated to be a key prosecution witness against Tanabe, and Wielsch have pleaded guilty to an array of charges including drug offenses, conspiracy and civil rights violations.

Butler was sentenced to eight years in prison and Wielsch, the former commander of the now-disbanded Central Contra Costa County Narcotics Enforcement Team, was sentenced to 14 years.

Among other crimes, Butler admitted to staging DUI arrests and extorting protection money from employees of an illegal massage parlor that he and Wielsch founded.

Tanabe's defense attorney said he didn't dispute that Tanabe participated in the DUI arrests, but said officers in the low-crime town had performance objectives that included making DUI arrests, and said it was normal for them to wait outside bars to watch for intoxicated drivers.

Butler admitted to staging a total of 12 dirty DUI arrests in various Bay Area locations. The three DUI arrests in which Tanabe participated occurred after the targets left bars and drove off in their cars on Nov. 2, 2010, and Jan. 9 and 14, 2011.