Uber is threatening to pull out of Maryland if a law goes into effect next month mandating the service require fingerprint background checks its drivers, and it joined rival Lyft in a hearing Thursday requesting a waiver on the requirement.

In testimony before the Maryland Public Service Commission, the companies were expected to argue that the fingerprint-based checks would be a costly and unnecessary burden, and a barrier for drivers to join the services. Uber has about 30,000 drivers in Maryland and has provided more than 10 million rides in state in the past two years, according to figures provided by the company.

Ride-hailing regulations adopted last year specified the companies must require fingerprint-based checks by Dec. 15. Supporters of the fingerprint scanning say the enhanced checks, conducted by Maryland police agencies and the FBI, would ensure that drivers with criminal records wouldn’t be able to work for the platforms. San Francisco District Attorney George Gascón, who jointly filed a California lawsuit alleging Uber improperly screened drivers, said in a 2014 news conference a background check that does not include fingerprint scanning is “completely worthless.”

Uber argues that fingerprint-scanning, which it calls “rap sheet”-based testing, is less accurate than checks conducted by private firms such as Checkr, the firm it uses.

But detractors of the ride-hailing services’ electronic checks argue that they have allowed offenders to slip through the cracks, endangering passengers. In one case from May, an Uber driver was arrested in connection to the attempted murder of two police officers in Gaithersburg, Md. Jonathan Hemming was arrested on the charges after he tried to shoot police officers with a homemade handgun, authorities said.

Critics were dumbfounded that Hemming, who had a lengthy rap sheet including felony convictions in three states, managed to secure a job working for Uber.

“How did Jonathan Hemming pass Uber’s background check? Uber’s private background checks can’t fully and reliably access and report out an individual’s criminal history,” said Dave Sutton, spokesman for ‘Who’s Driving You?,’ an initiative of the Taxicab, Limousine & Paratransit Association.  “This dangerous felon would never have passed a fingerprint-based criminal background check conducted by state law enforcement and the FBI. The evidence is already clear: Uber cannot be trusted to self-regulate when it comes to safety.”

But in testimony before the PSC, Uber expresses continued confidence in its background checking mechanism, which screens drivers based on criminal history, motor vehicle records, state and national sex offender registries and national terrorism watch lists, according to the company.

In expert testimony, Uber’s witnesses are expected to raise concerns about the accuracy of fingerprint-based checking and argue that such methods disproportionately target black and hispanic communities.

“I can say to and beyond a reasonable degree of professional certainty, that it is common that criminal record reports generated by [Criminal Justice Information Services] and the FBI are neither comprehensive nor accurate,” Glenn Ivey, former State’s Attorney for Prince George’s County, Maryland and a former Assistant U.S. Attorney in Washington, D.C., said in testimony provided in advance of the hearing. “Furthermore, these incomplete and inaccurate records disparately impact African Americans and Latinos.”

In a statement, Lyft decried fingerprinting as “decades-old technology with significant limitations.”

By relying on incomplete federal data and outdated arrest records, fingerprinting disproportionately disadvantages minority communities,” spokesman Adrian Durbin said in a statement. “In contrast, the modern background check process we use in Maryland is comprehensive and rigorous, pulling data directly from national and local court databases that are up-to-date, while still encouraging part-time drivers, who make up the vast majority of our Maryland community, to drive with Lyft.”

The hearing is scheduled to last three days. Public Service Commissioners are expect to rule on the matter by Dec. 15.