A Metropolitan Police constable admitted in court on Monday he called a suspect a "nigger" but claimed it was not intended as racial abuse.
In an exchange recorded on a mobile phone, PC Alex MacFarlane (pictured), 53, told 21-year-old Mauro Demetrio: "The problem with you is you will always be a nigger'."
He added: "Be proud of who you are, don't hide behind your black skin."
The incident took place on August 11 last year after Mr Demetrio was arrested on suspicion of drink or drug-driving and taken to Forest Gate police station. No further action was taken for the alleged offence.
Southwark Crown Court heard PC MacFarlane had confessed to saying the word "nigger" but that he had used the term after Mr Demetrio had done so first.
PC MacFarlane claimed the suspect said: "Let the white boy go, keep the nigger," after a white passenger travelling with Mr Demetrio at the time of his arrest was not detained.
Giving evidence, the defendant said he remembered Mr Demetrio calling officers "white cunt" as he was detained in a police van.
"I tried to calm down Mr Demetrio because of his racist abuse towards the police. I challenged him about his language," he said.
The trial was previously told Mr Demetrio had become "abusive" after he was allegedly throttled and pushed up against the window of a police van by another officer.
He used his mobile phone to record a heated exchange with officers.
One recording included an officer calling Mr Demetrio a "scumbag" and a "cunt," while a second recording included PC MacFarlane's alleged racial insult, it was claimed.
PC MacFarlane denies a charge of racially aggravated intentional harassment, alarm or distress.