Sub.-Lt. Jeffrey Paul Delisle, posted to the security unit HMCS Trinity, is charged with passing on secret information to a foreign country or entity.
The preliminary hearing will be held on Oct. 10 and 12, and a trial is expected to last about three weeks, depending on the availability of the judge.
Mike Taylor, Delisle's lawyer, says his client faces a mountain of challenges.
"I expect there will be pre-trial applications with respect to what can be public and what can't. The jury is obviously going to have to be given, I would assume, additional cautions with respect to sensitive material they might hear," Taylor said. "There are going to be some challenges, there's no question about that."