Trial By Magic sees Phoebe being called up for jury duty and serving on the case of a man accused of murdering his girlfriend. Phoebe gets a premonition revealing that the man is innocent, and she must convince the rest of the jurors of his innocence, without exposing magic in the process. Meanwhile, Glenn visits and turns himself into Mr Fantastic for 20 minutes. Cue hilarity. Or maybe not.
The jury duty storyline is, unsurprisingly, garbage. Alyssa Milano doesn't convince when going on and on about how difficult her situation is and the constant bathroom orbing sessions get annoying after a while. It would have been interesting to see Phoebe prove magic exists in a more practical way, instead of just warbling on about premonitions and psychics like some crazy homeless woman on a street-corner.
The whole "memory dust" thing is also a cheap excuse for a conclusion to the storyline. Why have we never been told of this before? It would have helped a lot when the sisters were exposed last season for instance. This is another example of why I hate Charmed. The writers think its okay to just create random get-out-of-jail-free-cards to bring the story to a climax, never thinking of the ridiculousness of it all.
Paige's subplot is also pretty pointless. Glenn is an extremely boring character and his sub-Mr Fantastic powers in this episode just don't work. Though it's neat to see Paige telling somebody about her witchy-ness, the storyline also makes Piper out to be a controlling bitch who should just can it more often. Her determination to keep Glenn out of the fold just doesn't make sense, seeing as he's known Paige since kindergarten.
The jury duty story is unexpectedly drawn to a close sorta quickly, leaving the fourth act with Glenn getting kidnapped by the demons responsible for the murder Phoebe is working on. It stinks of heavy re-writing and feels as if there wasn't enough material for a whole hour, so they just tagged on another mini-adventure involving the sisters battling a random demon-of-the-week to make it longer. Either way, it's still annoying.
Probably the weakest episode story-wise from season four, Trial By Magic is mind-numbingly tedious from beginning to end, with a lame A-story and a corny subplot. Avoid.