Model Kathryn Mayorga claims the Manchester United and Portugal superstar sexually assaulted her in a Las Vegas hotel bedroom in 2009.
Prosecutors decided not to pursue a criminal case in 2019, deciding the evidence was insufficient to prove guilt beyond reasonable doubt.
The 36-year-old footballer has always denied any wrongdoing.
Ms Mayorga launched a civil case against Ronaldo seeking damages.
Magistrate judge Daniel Albregts has now reviewed the case before a separate judge makes a final decision.
In a scathing recommendation, Judge Albregts blamed Ms Mayorga’s attorney, Leslie Mark Stovall, for inappropriately basing the damages claim on leaked and stolen documents from the Football Leaks data drop, shown to be privileged communications between Ronaldo and his lawyers.
“Dismissing Mayorga’s case for the inappropriate conduct of her attorney is a harsh result,” the magistrate wrote in his 23-page report to US District Judge Jennifer Dorsey. “But it is, unfortunately, the only appropriate sanction to ensure the integrity of the judicial process.”
“Stovall has acted in bad faith to his client’s – and his profession’s – detriment,” Judge Albregts decided.
Mr Stovall and other attorneys in his office did not immediately respond to requests for comment.
Ronaldo’s lawyer in Las Vegas, Peter Christiansen, issued a statement saying the footballer’s legal team was “pleased with the court’s detailed review…and its willingness to justly apply the law to the facts and recommend dismissal of the civil case against Mr Ronaldo.”