Definition: partisan; having a point of view
This is often applied to journalism, particularly the coverage of politics or issues that have a political aspect.
Why I Looked It Up
From a book about the media coverage of science news:
Reporters eager to avoid tendentiousness or editorializing – that is, eager to give both sides – can wind up in a kind of analytical passivity that leaves them with he-said-she-said stories that simply shift the burden of interpretation to the readers, who are even less equipped for the job than they are.