Lawsuits filed by nearly 40 U.S. veterans who sued 3M Co. for defective earplugs and hearing loss have been moved to federal court.

The cases were moved from Hennepin County District Court to the federal court in Minnesota at the request of 3M, court records show. 3M has denied wrongdoing in the cases.

The complaints are the latest of at least 635 veteran lawsuits making similar allegations against 3M and Aearo Technologies, which 3M bought in 2008.

The lawsuits — the first of which a military veteran filed in December 2018 — represent more than 1,700 individuals, according to documents 3M filed with U.S. regulators in April.

More lawsuits are expected, plaintiff attorneys said.

In summer 2018, 3M did not admit guilt but agreed to pay U.S. military branches $9.1 million to settle government allegations that the Maplewood-based company supplied defective earplugs. That settlement opened the door for individual veterans to sue 3M and Aearo, the attorneys have said.

Some of the cases have already been or are in the process of being rolled into a multi­district litigation (MDL) case being handled by a federal judge in the Central District of Florida.

Lewis Remele, the Minneapolis attorney representing Army veteran Chris Stephens of Georgia, said in an e-mail Wednesday that a federal judge decided in April 2019 to assign many of the earplug complaints against 3M and Aearo into one MDL case that will be handled by the judge in Florida. Remele did not know when the first MDL hearings could begin.

In MDL cases, a preliminary trial is usually held to establish key answers to at least one of the cases. The outcome of that first case is expected to set a precedent for how future, similar cases are handled. The lawsuits transferred to federal court last week could also eventually be transferred to Florida, the plaintiff attorneys said.

The lawsuits involve the "dual-ended combat arms ear plug" that 3M or Aero Technologies sold to the U.S. military as a way for thousands of service members to protect their hearing during combat missions in Iraq and Afghanistan or during training exercises stateside.

The earplugs were supposed to protect hearing while giving users two options. The wearer could insert the "green" end of the earplug into the ear to significantly block all sound. Or the user could insert the "yellow" end of the plug into the ear, so that critical "low-level" commands — but not loud, damaging noises —could be heard in the field.

The veterans' lawsuits reference company records to contend that Aearo and 3M knew the plugs were not long enough and did not work properly at the time the companies were marketing them.

The plaintiffs also contend the product failure caused permanent hearing damage and tinnitus, a form of ringing in the ear.

3M denies the allegations, said 3M spokeswoman Fanna Haile-Selassie.

In records 3M filed in federal court this month, 3M wrote that its Combat Arms Earplugs Version 2 (CAEv2) were designed by Aearo in close collaboration with the U.S. military and in accordance "with the military's rigorous specifications."

3M asserts immunity

Because of the military's heavy involvement in the earplug's development, 3M said in court filings it is immune from litigation and plans to assert the "federal government contractor defense" and the "combatant activities defense" if or when the cases go to trial. 3M said the military's involvement in designing the earplugs "went beyond merely establishing standards. Its involvement also included such operational features."

3M in court filings also called the earplug "a revolutionary breakthrough" because it helped service members maintain situational awareness in combat.

Dee DePass • 612-673-7725