The prosecution of James E. Holmes for the slaughter in a Colorado movie theater last month differs from most criminal proceedings because there is so little doubt that he is the perpetrator. But that will not make it easier.

Participants in the case, likely to be a drawn-out one, will wrestle with some of the most contested concepts in American law — sanity, an impartial jury and the political pressures for punishment in a deeply wounded community.

On Monday, Mr. Holmes sat glassy-eyed in a packed courtroom as the charges against him were made public — 24 counts of murder and 116 counts of attempted murder, two each for the 12 people killed and the 58 wounded on July 20 at the suburban cinema in Aurora where he was arrested in a commando-style outfit holding three weapons.

That moment in court, while preliminary, was telling. Mr. Holmes gazed at the ceiling lights, suggesting a mental state that his publicly appointed lawyers will focus on: Does he understand what is going on? Can he assist in his defense? Is Mr. Holmes competent to stand trial?