A former drug addict told a court a policeman kept her under his control for four years after he made her perform a sex act after arresting her.
The woman told Newcastle Crown Court Pc Stephen Mitchell also gave her money to buy heroin when she was trying to quit.
The 42-year-old Northumbria police officer, of Glasgow, denies five counts of rape, six of indecent assault and 15 of misconduct in public office.
The offences are alleged to have happened between 1999 and 2006.
Giving evidence from behind a screen, the woman, in her 30s, said her ordeal started in 1999 when she was arrested for obtaining property by deception.
The court heard she was taken to Newcastle's Pilgrim Street police station where he said that in return for him not charging her she would perform a sex act on him.
'Teach me a lesson'
She said over the next few years Mr Mitchell called on her regularly to perform a sex act on him in his car.
She said she had asked him repeatedly to give her a video he claimed he had of CCTV footage of her fraudulently cashing a benefits cheque at a post office.
The woman told the court Mr Mitchell raped her the last time she saw him in 2003.
She said by that time she had a job and a flat and she was scared she would lose them if the tape emerged.
She told the court the officer handcuffed her, claiming he was arresting her for fraud and then raped her.
She said: "He said he would teach me a lesson.
"[That] it was my own fault. [That] I was a junkie, nobody would ever believe me."
The officer helped her to get a place at a drug rehabilitation centre, she said, but she would have lost it if she had been charged with fraud.
The trial continues.