By Jonathan Stempel

(Reuters) - Taser International Inc is not liable for the death of a 16-year-old Michigan boy soon after he was struck in the chest by two taser darts shot by a police officer, resulting in cardiac arrest, a federal appeals court ruled on Friday.

The 2-1 decision by the 6th U.S. Circuit Court of Appeals in Cincinnati was a defeat for Cora Mitchell, whose son Robert died on April 10, 2009 after a Warren, Michigan police officer struck him with electronically charged darts from his X26 taser, after a chase on foot into an abandoned home in nearby Detroit.

Shares of Taser rose about 5 percent within 1-1/4 hours of the release of the decision.

Taser's electrical weapons are popular with police, and the Scottsdale, Arizona-based company said more than 18,000 law enforcement agencies have bought them since 1994. Critics say the weapons are susceptible to misuse.

Cora Mitchell said Taser should have warned police that using the X26 could cause cardiac arrest, and that its training program negligently assured users about the device's safety.

Writing for the appeals court majority, however, Circuit Judge Jeffrey Sutton called the alleged risk "speculative," and said a company "does not have a duty to warn of all theoretically possible dangers."

He also said the negligence claim must fail because an independent contractor had trained Warren police on the X26, and Taser had no "perpetual duty" to warn about the potential risks.

The decision upheld a lower court ruling.

Circuit Judge Bernice Bouie Donald dissented, saying there were unanswered questions about the extent of Taser's duty to warn about the X26's risks prior to selling the device.

"We're terribly disappointed in the decision," Bill Goodman, a lawyer for Cora Mitchell, said in a telephone interview. "It has basically bought into Taser's propaganda, that Taser had no information that its product could cause injury or death."

Goodman said his client may ask the full appeals court to review the case.

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Taser spokesman Steve Tuttle said the decision showed that "litigation against Taser based on speculative medical causation theories and mere possibilities, instead of probabilities, will not suffice."

Cora Mitchell also sued Warren and several police officers over her son's death, and settled for undisclosed terms.

Taser shares closed down 41 cents, or 1.9 percent, at $21.29 on the Nasdaq, after earlier rising to $22.08.

The case is Mitchell v. Taser International Inc, 6th U.S. Circuit Court of Appeals, No. 14-2075.





(Reporting by Jonathan Stempel in New York; Editing by Frances Kerry)