The book starts with a man on trial, he has no idea why as he is missing a big chunk of his memory.
He fires his attorney, and the court goes with some type of memory retrieval.
We witness what happened in the past: a space ship is boarded, a military campaign on a planet.
There is a comment as to why he prefers the shotgun: it is great for crowd control.
There are several aliens: a group hiding on the mentioned planet and some are also present at the trial.
At the end we learn that the reason why he did not trust his attorney was becouse he was given a subliminal suggestion to not trust a person with a tie of a particular color.
I listened to the story between 2010 and 2014, and it seemed pretty recent at that time. And it is a story set in the future, when Earth and humans are part of the wider galaxy.
EDIT: The weapon is a shotgun and not the bayonet as I thought previously.