Against all enemies - John G. Hemry

John G. Hemry's novels featuring Lieutenant Paul Sinclair "give SF its own JAG" (SF Reviews.net). Now, in the final novel in the series that melds science fiction action and page-turning courtroom drama, Sinclair finds
himself fighting for justice once more-and the danger is closer than ever
before

After a long tour as legal officer aboard the starship USS Michaelson, Paul Sinclair is
anticipating shore duty. Too bad it's cancelled when a group of religious
fanatics hijack a freighter and invade an asteroid. Fearing they could
threaten the earth with asteroid debris, starships from several countries
converge on the scene. But their mission turns deadly when the South Asian
Alliance opens fire on the asteroid.

After the smoke clears, Paul suspects the Michaelson's rules of engagement have been compromised-suspicions that
are confirmed when NCIS asks him to work covertly as a spy. Someone onboard
the Michaelson is
selling secrets, and to uncover the traitor, Paul must walk the dangerous
line between duty and honor