The defense attorneys are asking for a delay in the death penalty case until the marriage question is resolved.
The move could delay the March trial by several weeks to a year.
Wade is accused of kidnapping and killing Mindy Schloss, a 52-year-old nurse practitioner who lived next door to him. Her body was found in September 2007 in a wooded area of Wasilla after she had been missing for weeks.
Lawyers for Wade, now 29, say he legitimately married his intermittent girlfriend Lisa Andrews, 46, in a telephone ceremony, thereby invoking the spousal privileges that bars her from testifying against him.
Andrews is a witness for the prosecution.
"If Lisa Andrews Wade is forced to testify or otherwise reveal privileged communications, Wade will suffer serious prejudice," wrote Wade's attorney, Suzanne Lee Elliott, in a motion to delay all court proceedings.
Elliott also wrote that "important strategic defense decisions depend upon resolution of this issue."
U.S. District Court Judge Ralph Beistline ruled the marriage "void" Sept. 2. He wrote in his order that because it was conducted by telephone, it violated Alaska law, which requires that people getting married do so in each other's presence.
Prosecutors say the marriage was a farce to prevent Andrews from testifying.
Beistline said that even if the marriage was validated, spousal privileges probably would not apply because the reason for the marriage was suspect.
The application for the appeal was filed Monday in the Ninth Circuit Court of Appeals.
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