Judge Patrick Dugan delivered the ruling against former police lieutenant Jonathan Josey last week.
Soon afterwards, information came out that the judge is married to a Philadelphia police officer who was in the courtroom during the proceedings.
Now a women's group is calling on others to join them in the chorus of leaders calling for a federal investigation by the U.S. Department of Justice.
"There's no possible way that you can be endorsed by the FOP, be married to a police officer, that police officer can have presence in your courtroom and that you can make an unbiased decision, there's just no way," said Quetcy Lozada, National Coalition of Puerto Rican Women.
Earlier Friday, outside City Hall, angry demonstrators denounced the controversial verdict.
Josey was videotaped punching Aida Guzman at the Puerto Rican Day parade last September. The woman was struck in the face and fell to the ground.
During his trial, Josey testified that he was trying to knock a beer bottle out of Guzman's grasp.
"Everyone of us could be Aida Guzman, your mother, your grandmother, your sister, your aunt. This is about justice," said Councilwoman Maria Quinones-Sanchez during the protest.
Judge Dugan called video disturbing but says there was insufficient evidence to convict Josey of simple assault.
What Dugan did not disclose before hearing the case is that he is married to Philadelphia Police Sgt. Nancy Farrell Dugan.
Experts say that's information that should have been disclosed.
Philadelphia District Attorney Seth Williams said in a statement that he was unaware about Judge Dugan's wife and the conflict of interest.
Guzman's attorney Enrique Latoison calls it a miscarriage that should be thoroughly investigated by the U.S Dept of Justice.
"To make sure that the justice is done properly, fairly and done correctly in this matter," said Latoison.
In calls to the U.S. Attorney's Office in Philadelphia and the Department of Justice, Action News was told that they do not comment on matters they may or may not investigate.