Lil Mosey Claims Alleged Rape Victim Admitted to Prior Consensual Sex

Lil Mosey says the alleged victim in his rape case admitted to having consensual sex with him in the past, and he's asking the court for the green light to introduce that evidence at trial.

According to new legal docs obtained by TMZ ... the rapper claims he met the alleged victim back in the day at one of his concerts, and they eventually engaged in consensual sexual activity ... multiple times.

Lil Mosey claims they had sex at a New Year's party, and then again in a car. He says that the second time happened on the same night of the alleged rape, which she alleges happened later in a cabin.

TMZ broke the story ... Lil Mosey was charged with rape back in April with the woman claiming she blacked out from drinking and woke up to Mosey and another man forcing themselves on her. Mosey's pled not guilty.

The case is being tried in Washington, and the state has a "rape shield" statute that generally prohibits evidence of prior sexual relationships and activities with an alleged victim at trial.

However, Lil Mosey is arguing the evidence of a prior consensual sexual relationship should be admitted because he believes it helps him defend against the allegation she did not consent.

Prosecutors are pushing back against allowing the evidence in court. In new legal docs, they say the alleged victim's prior sexual activity is irrelevant to whether she consented, adding he's been charged with second-degree rape which involves an alleged victim who is incapable of consent.

In this case, the woman claimed she had blacked out from drinking and could not possibly have consented.