Cornell 7 frat brother Gillio Lopes' legal team is slamming New York Attorney General Letitia James over her explanation for why she called Jane Doe a survivor ... TMZ has learned.

In new legal docs, obtained by TMZ, Lopes' attorneys rejected James' characterization of her remarks as "mere empathy" ... and argued that declaring Jane Doe's account to be true before being appointed as special prosecutor seriously undermines her ability to perform an unbiased investigation.

We reported earlier ... James wrote on social media before being tapped to oversee the investigation ... "What this young woman has been forced to endure is horrific and unacceptable. I'm holding her in my heart and in my prayers. To her, and to all survivors: you're not alone. We stand with you."

Lopes' legal team says that by referring to Jane Doe as a survivor, James has compromised the fairness of the probe.

And in response to critics who say that their filing is premature because James hasn't filed charges yet ... Lopes' attorneys say that her alleged bias will have an effect on the evidence-gathering process, assessing the credibility of witnesses, and presenting evidence to a grand jury.

As you know ... James has since backpedaled on her remarks ... claiming that she was expressing empathy, not revealing a bias.

Lopes' legal team wants James to be disqualified as a special prosecutor ... or removed from any participation in the probe.

And if a court turns them down ... Lopes' attorneys want it ordered without prejudice -- meaning they retain the right to seek her disqualification again as things develop.