Peterborough's Labour MP has appeared in court charged with perverting the course of justice after allegedly lying to the police as to who was driving a speeding vehicle in order to avoid getting penalty points on her licence.
The Peterborough MP, a qualified solicitor who won the key marginal seat in 2017, appeared at Westminster Magistrates' Court on July 12.
Court records show she was charged over allegedly lying about who was behind the wheel of a speeding vehicle.
The Crown Prosecution Service said Onasanya faces two charges of perverting the course of justice and will appear at the Old Bailey on August 13.
She is alleged to have been behind the wheel of a speeding vehicle on July 24 2017 but together with her brother Festus Onasanya told the authorities someone else was driving.
The second similar count relates to an incident on August 23 2017 when her brother was alleged to have been driving.
Cambridgeshire Police confirmed that "Fiona Oluyinka Onasanya, 34, from Peterborough" had been charged with perverting the course of justice.
"She appeared at Westminster Magistrates' Court on July 12 and is due to appear in court again on August 13," a police spokesman said.
A Labour Party spokesman said: "It would not be appropriate to comment on an ongoing case."
Ms Onasanya, who was a solicitor before her election to Parliament, is a Labour whip, meaning she is responsible for party discipline.
She won the Peterborough seat with a majority of just 607 votes, ousting Tory Stewart Jackson.
The former Conservative MP then took up a role as David Davis' chief of staff until the then Brexit secretary quit earlier this month.
Former MP Chris Huhne and his ex-wife, Vicky Pryce, were each jailed for eight months in 2013 for perverting the course of justice over an arrangement in which Pryce took speeding points for the former Liberal Democrat MP