The current canon policy of Parmount for Star Trek is that only the movies and televisions series are considered canon.

In contrast Lucasfilm has made their policy more complicated but no less valid. That being that movies, internal notes from George Lucas, and movie novel adaptations are the highest canon. Following that is the television series The Clone Wars. Then the various videogames, novels, comics, and various sourcebooks. If there is an explicit contradiction between higher canon and lower canon, higher canon wins out. Finally are items explicitly noted as non-canon such as the Infinities series.