O'Neill's attorney, James Berardinelli, filed the motion Thursday after prosecutors completed their case against the two defendants.
Such defense motions are often filed after the prosecution case. Basically, Berardinelli will argue that the charges against O'Neill should not go to the jury because prosecutors did not prove them beyond a reasonable doubt.
Motions for acquittal are not commonly granted, although judges sometimes are persuaded to dismiss some charges, which could result in a lighter sentence if the defendant is convicted on other counts.
For 31 years, Gosnell, 72, owned and operated the Women's Medical Society clinic at 3801 Lancaster Ave., where he had a family medical practice and also did abortions.
Gosnell is charged with seven counts of first-degree murder for allegedly killing babies born alive and viable during late second-trimester abortions. If he is found guilty, Gosnell could be sentenced to death.
McMahon has argued that none of the babies born alive would have survived because of the chemical used in late second-trimester abortions.
Gosnell is also charged with third-degree murder in the 2009 death of a Virginia patient who prosecutors allege was given too much Demerol during an abortion procedure by Gosnell's untrained staff.
O'Neill, 56, of Phoenixville, who worked in the family-medicine practice at Gosnell's clinic, is not charged with performing abortions. She is charged with working as a doctor without a medical license and participating in the operation of a corrupt organization.
Contact Joseph A. Slobodzian at 215-854-2985, firstname.lastname@example.org, or follow on Twitter @joeslobo.