Two rivals of medical artificial intelligence platform OpenEvidence have told a Massachusetts federal judge the startup has used the courts in a campaign of "deceit, harassment and defamation" against competitors.

In an amended counterclaim filed Monday, San Francisco-headquartered Doximity and Pathway Medical Inc. say OpenEvidence "has chosen unfair competition at its worst," while allegedly misleading doctors and the public about its own capabilities and limitations.

"Rather than focus time and money on developing technology to ensure that patients receive the best medical care as quickly as possible, which is Doximity's preferred pursuit, OpenEvidence spends its resources on a smear campaign against its competitors," Doximity and Pathway say in the counterclaim, which seeks damages for defamation, false advertising and unfair and deceptive business practices.

The filing comes after OpenEvidence last month amended its original lawsuit from June, dropping its central claims that Doximity had stolen its "crown jewel" trade secrets, and instead pursuing allegations of breach of contract, improperly accessing OpenEvidence computers and unjust enrichment.

OpenEvidence had made similar allegations against Pathway Medical, a Canadian platform that was acquired in August by Doximity, along with a third company, Veracity Health, based on claims that the rivals had attempted to trick its chatbot into divulging source code through deliberately phrased inquiries, at times by misrepresenting themselves as medical professionals.

The counterclaim alleges OpenEvidence then used news coverage of the lawsuits to target its rivals' customers and business partners, before withdrawing the trade secrets claims.

OpenEvidence also went beyond using the courts to target and undermine its rivals, secretly creating bogus social media accounts with links to news sites that were also created by the company, and making and trying to spread false claims about Doximity and Pathway, according to the complaint.

At the same time, OpenEvidence has made false assurances of privacy controls and HIPAA compliance, and false claims of accuracy, to medical providers and advertisers, as well as overstating its number of users and even its ranking in Apple's App Store, according to the filing.

The counterclaim offers as an example instances where information about specific patients wound up being publicly available on OpenEvidence's site, and the company's alleged practice of selling information about physician inquiries to advertisers.

Doximity said OpenEvidence also sought to raid its workforce by suggesting that it would win a "billion dollar" lawsuit against the California company.

The filing includes a copy of an Aug. 31 email allegedly sent by OpenEvidence founder and CEO Daniel Nadler to Doximity's then-general counsel, after OpenEvidence hired one of Doximity's employees, in which Nadler said, in part, "y'all are utterly impotent to retain your own talent, it might dawn on y'all that the planetary show must indeed go on, the species must indeed continue with someone's seed, and perhaps we all just set differences aside and do one clean for the ecosphere."

Nadler went on in the email to describe how he has "been going deep lately on the Late Eastern Han Dynasty in 2nd Century China," and signed the email with "Hugs and high-fives," according to the complaint.

"While such tactics may have been permissible in the violent feudal competition that characterized the Late Eastern Han Dynasty — the historical time period that Mr. Nadler gloated about 'going deep … on' in one of his bizarre emails to Doximity — the law has since evolved to forbid them," the company says in its filing. "OpenEvidence's ongoing campaign of misinformation violates federal and state law and must stop."

Pathway has also faced similar tactics, according to the counterclaim, which cites an example of an ad agency client that rescinded an invitation for Pathway to present at one of its events after contact with Nadler.

After the acquisition was announced, Nadler allegedly emailed Pathway's founders, "You go and sell your whole company for less cash than I just paid for one of my apartments."

"As we've said previously, we believe this entire effort was designed to use litigation as marketing — to generate false and misleading narratives about Doximity to gain an unfair advantage," a spokesperson for Doximity said in a statement. "Our goal now is simply to set the record straight and get back to serving doctors."

Nadler, responding to a request for comment from the company, accused Doximity of engaging in the sort of behavior it alleges against OpenEvidence.

Nadler, referring to Doximity's complaints that OpenEvidence placed undisclosed sponsored content on social media, alleged that Doximity had previously failed to disclose a prior consulting arrangement with the author of a newsletter who published a comparison of the two companies. Nadler complained that Doximity's lack of disclosure violates Federal Trade Commission guidelines. He also cited a news report concerning a shareholder lawsuit brought against Doximity earlier this year.

Doximity Inc. and Pathway Medical Inc. are represented by James R. Carroll, William E. Ridgway, Brian O'Connor, Bijal V. Vakil and Will Wray Jr. of Skadden Arps Slate Meagher & Flom LLP.

OpenEvidence is represented by Stephen Broome, Nathan Hamstra, Stacylyn M. Doore, Ryan P. Gorman, Vanessa Rodriguez and Zi Chun Wang of Quinn Emanuel Urquhart & Sullivan LLP.

The case is OpenEvidence Inc. v. Doximity Inc. et al., case number 1:25-cv-11802, in the U.S. District Court for the District of Massachusetts.