The engineers said lead issues at the water treatment plant were out of the scope of their work for the city. They argued that city and state officials were actually to blame, claiming they had ignored the firms' recommendations that could have prevented or sooner identified the problem. The case was expected to serve as an indicator of whether engineering firms could face further liability for other injuries related to the tainted water.

Federal Magistrate Judge David Grand declared a mistrial in the case against Boston-based Veolia and Houston-based LAN, a unit of Leo A Daly, in U.S. District Court in Ann Arbor, Mich., after jurors said they would be unable to reach an agreement. 

“I believe that the jury has made clear that they are hopelessly deadlocked after a valiant effort to reach a unanimous verdict,” Grand said. 

The decision followed a nearly five-month-long trial and weeks of deliberations. In a note to Judge Grand, who was handling the case after U.S. District Judge Judith Levy stepped away due to a medical issue, jurors wrote that they did not believe they could continue deliberations “for the physical and emotional health of the jurors.”

They said that “Further deliberations will only result in stress and anxiety with no unanimous decision without someone having to surrender their honest convictions solely for the purpose of returning a verdict.”

Moshe Maimon, an attorney representing the families of children who allegedly suffered neuro-cognitive injuries as a result of drinking lead-tainted water, asked Grand to interview jurors individually about the case and what physical or mental health issues they were facing by continuing to deliberate, citing cases that dealt with jurors who were mentally or emotionally unstable. He asked Grand to consider a verdict based on the agreement of seven-of-eight jurors, rather than a unanimous verdict. 

Attorneys for Veolia and LAN requested a mistrial based on the jury’s note. Cheryl Bush, representing Veolia, and Wayne Mason, for LAN, said federal court rules require a unanimous verdict, and court instructions to jurors also specified that they were tasked with reaching a unanimous verdict. Asking anything else of jurors would be “totally inappropriate,” Mason told the judge. 

This was not the first time jurors on this case shared that they were having difficulty reaching a verdict. Grand said jurors had previously sent notes while Levy was still presiding over the case and again once he had taken over, and were instructed to continue deliberating. The district court released the notes to the public.

The judge added that questioning jurors individually would put them under “undue pressure,” and that the notes indicated the lack of consensus did not seem to be a single-juror issue.

“I find that if I were to have them deliberate any further, question them any further, it would improperly influence the jury, and result in an outcome that did not truly reflect the will of this jury,” Grand said.

Mason thanked the jurors for their service and said the deadlocked jury was the result of the plaintiffs being unable to meet their burden of proof in the case. "The fact that the plaintiffs could not make their case to this jury underscores what the state’s own investigation found: there was an epic failure of government," he said in a statement. 

Flint's drinking water crisis began after the city switched its water source from the Detroit Water and Sewerage Dept. to the Flint River in April 2014 as a cost-saving measure. The city's water treatment plant was unable to prevent corrosive water from reaching lead pipes, causing lead to leach into drinking water.

The two firms were not part of the earlier $625-million state settlement related to Flint’s lead water contamination and its resulting problems. This suit was to be a bellwether case potentially determining the engineers’ liability for others impacted by the contaminated water.

LAN had worked for Flint prior to the source switch, but its work did not include treatment plant operations. LAN employees testified that they had recommended corrosion controls such as orthophosphate.

Flint later hired Veolia in 2015 to review issues at its water treatment plant other than lead, and its employees also said they recommended a corrosion control study which would have revealed the need to address the issue. Attorneys representing the firms argued that officials had dismissed recommendations because they were focused on saving money, as the city's finances were under review by a series of state-appointed emergency managers the entire time the firms were employed as consultants.