In a complaint published on Tuesday, the Public Utilities Commission of California says it reviewed 154 “zero tolerance” complaints about Uber drivers between August 12, 2014 and August 31, 2015—and that the company only conducted any sort of investigation in 21 of those cases.

The regulator also found Uber attempted to contact the driver in only 50 of those cases and that, in at least 25 cases, the company failed to suspend or investigate drivers facing three or more complaints. And in multiple situations, data reportedly showed that drivers cited for impaired driving stayed on the road picking up Uber customers—even when the company had technically suspended them.

As a result of the investigation, Uber faces a fine of $7,500 for 151 separate violations for a total of $1,132,500. The company has 10 days to file a response to the regulator’s findings.

Uber declined to offer a formal comment. But a source close to the company noted the period in question was 2014 and 2015, and said the company has since improved its compliance and record-keeping. The source also pointed to guidelines saying Uber has zero tolerance for impaired driving.

Under California law, ride-hailing companies like Uber and Lyft are exempt from a random drug and alcohol screening program imposed on other commercial driving operations—provided the companies implement a series of “zero tolerance” measures to take action on impaired drivers.

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The zero tolerance measures include providing customers with a way to flag drivers under the influence (including phone an in-app contacts) and promptly investigating drivers who are the subject of complaints.

According to the regulators’ report, Uber’s system didn’t provide a way to promptly flag impaired drivers, but instead lumped such warnings in with general complaints. The report also concluded all four of Uber’s methods for confirming a complaint— including a driver’s admission and video evidence—to be “problematic” and two of them to be totally unrealistic:

[Uber]’s second option to receive an arrest/conviction requires a police officer to be present and pull over the driver. And Option 3, the alcohol blood test, similarly relies on a third party to conduct the test and provide the results to [Uber]. Both Options 2 and 3 contradict [Uber]’s own practices, as [Uber] does not attempt to obtain any physical evidence in its zero tolerance investigations

Finally, the report, spotted by SF Gate, suggests that reports of impaired driving by ride-hailing companies are widespread in California. While the regulator appeared to review only 154 of the Uber complaints, it states the company received a total of 2,074 complaints during the one-year period in question.

The controversy comes as Uber seeks a COO to help its embattled CEO, Travis Kalanick, address what many regard as a problematic “bro culture” at the company.

This story was updated at 1:55pm ET to add Uber’s response.