Sentencing began Tuesday in the case of 21-year-old Dzhokhar Tsarnaev, who a jury earlier this month found guilty of all 30 counts stemming from the deadly Boston Marathon bombings two years ago. Much of the public discussion has turned to the death penalty, and will—and should—Tsarnaev receive that punishment. Here, Daniel Medwed, a professor in the School of Law and an expert in criminal law, discusses the sentencing proceedings and examines the possibility of capital punishment.

How will the sentencing phase differ from the trial phase in this case?

Because Tsarnaev is facing the prospect of capital punishment, the same jury impaneled for the “guilt phase” will now determine the appropriate punishment at the sentencing phase, unlike most criminal cases where the judge makes that decision. The sentencing phase will resemble the trial in many respects but with somewhat relaxed evidentiary rules and a few important wrinkles.

First and foremost, the jury faces a binary choice: a sentence of death or a sentence of life without the possibility of parole. The jury must unanimously vote in favor of death for that sentence to apply; if even one of the 12 jurors remains unconvinced of the propriety of capital punishment, then Judge O’Toole must sentence Tsarnaev to life in prison without parole. I should note that if Tsarnaev were to receive a life sentence, he would probably serve it in the federal “super-max” facility in Colorado, where he would spend 23 hours a day alone in his cell.

Second, to justify the ultimate penalty, the prosecution must prove what one might call “guilt plus.” Namely, prosecutors must prove one or more statutorily prescribed aggravating factors beyond a reasonable doubt. These potential factors include claims that the crimes were particularly cruel, heinous, and depraved; involved substantial planning and preparation; and targeted vulnerable victims.

Third, I anticipate a much more robust defense presentation in this phase of the case than in the last one. The defense is entitled to put forth “mitigating factors” designed to persuade the jury to spare Tsarnaev’s life. A host of mitigation avenues seem available to the defense, such as arguments that he acted under duress at the hands of his brother, Tamerlan, that he was a lesser participant compared to Tamerlan, and that he was only 19 years old at the time. The defense may present family and friends to buttress a theme, which it alluded to during the guilt phase, that Jahar was the follower and Tamerlan the leader in their sibling relationship. The defense may also put on evidence about research concerning adolescent brain development to suggest that the part of the brain that governs rational decision-making is not necessarily fully developed in a teenager.

Nearly two weeks passed between Tsarnaev being found guilty and the start of the sentencing phase, during which time the two-year anniversary of the bombings took place. Could this gap have an effect on the prosecution, defense, or jury during the sentencing phase?

It’s hard to say. The jury returned its verdict relatively quickly given the complexity of the case—Tsarnaev was convicted of all 30 charges after less than 12 hours of deliberations. This signaled to me, at least, that the jury may have been quite moved by the prosecution’s case and that the prosecution had tremendous momentum heading into the sentencing phase. If this impression is correct, then the two-week gap could aid the defense by allowing some of the residual anger and disgust that jurors may have felt toward Tsarnaev to fade.

The fact that the hiatus coincided with several notable events—the second anniversary of the tragedy, the 20th anniversary of the Oklahoma City Bombing, and this year’s Boston Marathon–ideally should have no effect, provided that the jurors abided by Judge O’Toole’s admonition that jurors refrain from attending the Marathon, reading media accounts of the trial, and so forth. On Tuesday, during the opening day of the sentencing phase, the jurors asserted that they had adhered to these warnings.

Some of the victims and family members have called for taking the death penalty off the table. How do you expect victims’ views on the death penalty to factor into sentencing, particularly for the prosecution?

Let’s look at its likely legal, practical, and strategic impact.

Recent developments in which some victims and family members have expressed a preference for the prosecution to abandon its pursuit of the death penalty should have no legal effect at the sentencing phase. The law is clear that victims’ opinions about capital punishment are inadmissible at sentencing; they may distract, confuse, or otherwise unduly affect the jurors. Victims may testify about the impact that the crimes have had on their lives, but they may not stray into the realm of their opinions about the proper punishment.

As a practical matter, I doubt that these statements by members of the victim community, as dignified, graceful, and heartfelt as they are, will prompt prosecutors to offer an 11th-hour plea bargain, especially now that the sentencing phase has begun. Prosecutors do not formally represent victims; they represent the public as a whole. What is more, there are hundreds of victims in this case with presumably a wide range of views on the suitable punishment. In short, I do not envision that the prosecutors will all of a sudden reverse course here.

I do think, however, that the statements of some victims and family members in opposition to the death penalty could possibly alter the prosecution strategy at the sentencing phase. In particular, the appalling murder of 8-year-old Martin Richard figured prominently in the prosecution’s narrative during the guilt phase. Just last week The Boston Globe published a letter in which Martin’s parents urged prosecutors to offer Tsarnaev a deal for a life sentence. Out of deference to the parents’ stance, should prosecutors refrain from relying specifically on their son’s murder in making its case for capital punishment? An interesting moral question.