Aerosmith Steven Tyler’s Accuser Fighting to Keep Abortion Evidence Out of Court

Steven Tyler is fighting his teen abuse accuser over abortion evidence in their upcoming trial ... TMZ has learned.

According to new legal docs, obtained by TMZ, Steven and Julia Holcomb are going back and forth over whether the jury should be able to hear about two abortions Julia received.

Steven asked to exclude any evidence or reference to a 1975 abortion because he says it occurred in Massachusetts after she turned 18 and doesn't have any connection to sexual conduct in California.

However, Steven says if the judge does allow talk of the 1975 abortion, which would have been his kid, he wants permission to talk about a second abortion she got in 1979, when she was pregnant with another man's child.

Steven's legal team says Julia has "contended that the 1975 abortion was extremely traumatic and contributed to the emotional distress damages she is claiming in this matter" ... so allowing reference to it in the case should open the door to bringing in evidence about the later abortion to put everything in context.

The Aerosmith frontman says Julia has been a speaker on the anti-abortion circuit … where she spoke about “her regret of undergoing an abortion generally” and not just in reference to the 1975 abortion.

Tyler's lawyers insist "the fact that [Julia] voluntarily underwent a second abortion is probative as to the emotional distress she alleges she suffered from the 1975 abortion, and because [Julia] admits both abortions were traumatic, provides a possible alternative cause of her alleged mental condition."

The judge has yet to rule on Steven's request.

As TMZ first reported ... Julia claims Steven sexually abused her when she was a teen in the '70s. She says they began a relationship when she was just 16 years old.