MINNEAPOLIS — A Minnesota law banning the offering of advice or encouragement about how to commit suicide is an unconstitutional restriction on free speech, the state appeals court ruled Monday.

The decision by a three-judge panel of the Minnesota Court of Appeals was hailed as a “grand slam” victory by Robert Rivas, an attorney for the Final Exit Network. Two members of the national right-to-die group are charged in the 2007 suicide of Doreen Dunn, a 57-year-old Apple Valley woman who had suffered from chronic pain for more than a decade.

Prosecutors “don’t have one scintilla of evidence from the scene” to support the charges that the two Final Exit Network members assisted in Dunn’s suicide, Rivas said.

Monday’s ruling, which noted that the constitutionality of state’s ban on actively assisting in someone else’s suicide is already settled, sends the case back to Dakota County District Court. But Dakota County Attorney James Backstrom said he’ll ask the state Supreme Court to review the decision.

Both Backstrom and Rivas agreed it conflicts with a Court of Appeals ruling in another closely watched case that’s testing the same set of Minnesota laws against assisting suicide. Former nurse William Melchert-Dinkel, of Faribault, hunted for suicidal people in online chat rooms and encouraged them to kill themselves.

A British man and a Canadian woman who communicated with him took their own lives in 2005 and 2008, respectively. Melchert-Dinkel was convicted in 2011 of assisting them. The Court of Appeals ruled last year that his actions were not protected speech, but Monday’s decision came from a different three-judge panel.