There’s no question of did-he-or-didn’t-he here: the lawyer for Dzhokhar Tsarnaev, who is accused of bombing the Boston Marathon in April 2013 along with his now-deceased brother, said bluntly during opening statements that his client committed the act. So why exactly is a trial necessary at this point?

And yet, Tsarnaev pleaded not guilty to the crime. How is that possible when his lawyer admits that he did it? Because a plea of guilty would “result in them waiving all their appellate rights,” according to Robert Bloom, Boston College law professor, as quoted in an Associated Press report that attempts to answer this question.

His lawyer also wants a two-phase trial that will begin with the first phase and will help set up the arguments for the second phase, when they attempt to minimize his penalty.

Why not simply make these arguments in the penalty phase? The report quotes a death penalty specialist as saying that a competent death penalty defense lawyer will present themes during the first phase such as diminished capacity or diminished responsibility that will be consistent with what is said during the penalty phase. It’s fundamental to defend someone facing the death penalty by presenting a unified theme, so it’s not wise to say “my client is innocent” in the first phase and then say “my client is sorry” in the next. He called it “completely ordinary” what they were doing.

The courtroom is already set to be an emotional one, especially considering the violent nature of the events that took place nearly two years ago at the finish line of the Boston Marathon.

Dzhokhar Tsarnaev and his older brother, Tamerlan, packed pressure cookers with gunpowder as well as shrapnel such as nails and ball bearings, and then planted them along the street, setting them off in a violent explosion that tore bodies apart.

Tsarnaev allegedly stood for four minutes behind a crowd on Boylston Street before setting off a bomb. It killed an 8-year-old boy who was near the blast, as took off the leg of his 6-year-old sister.

A grad student from China was also struck by the blast, and bled to death.

A third person, a restaurant manager, lost her lower extremities due to the shrapnel, and she died holding her friend’s hand after complaining that her legs hurt.

Those violent, emotional images will be tough for the defense team to get around as it tries to ask the jury to consider there was some sort of justification for Tsarnaev that would require a reduced sentence.