How does the fact that felony murder is at least in principle murder without premeditation, factor in when the issue of the death penalty is being considered as punishment for the crime? Surely the death penalty should only be used on the most heinous of murder cases and not on those who are in some ways an accidental death.
While felony murder was an offense originally invented to single out more culpable murders from less culpable murders, with only the former punishable by death, as opposed to imposing the death penalty on everyone convicted of murder, it has evolved into a means of convicting someone of first degree murder who otherwise would not have been guilty of the crime of murder (or even conspiracy to commit murder) at all.
In a typical felony murder statute, everyone who participates in a felony designated in the felony murder statute that results in a death at the hands of any participate, without regard to premeditation or involvement in the murder itself, is guilty of felony murder, rather than merely the underlying felony crime.
Typically, felony murder is one way to be guilty of first degree murder and typically the punishment for first degree murder is either life in prison without possibility of parole, or the death penalty (if the state has death penalty), as determined in a second phase of the jury trial after the guilt phase is completed.
At the death penalty phase, following evidentiary presentation by the prosecution and the defense of aggravating and mitigating factors, in addition to the evidence presented in the guilty or innocence phase of the trial (at which the same death qualified jury convicted the defendant), the jury (except in Nebraska where a panel of three judges makes this decision, and in Montana where a sole judge makes this decision) must determine if the aggravating factors in the case outweigh the mitigating factors, if any.
The fact that the defendant (now a convicted murderer) was a knowing participant in a felony is typically an aggravating factor. The possibility, if established, that the defendant (now a convicted murderer) was not expecting that violence would occur and did not participate in the killing would be a mitigating factor.
The Supreme Court of the United States has held that the Eighth Amendment to the United States Constitution does not prohibit imposing the death penalty for felony murder. The Supreme Court has created a two-part test to determine when the death penalty is an appropriate punishment for felony murder. Under Enmund v. Florida, 458 U.S. 782 (1982), the death penalty may not be imposed on someone who did not kill, attempt to kill, or intend that a killing take place. However, under Tison v. Arizona, 481 U.S. 137 (1987), the death penalty may be imposed on someone who was a major participant in the underlying felony and acted with reckless indifference to human life.
So, the constitutional standard for imposing the death penalty for felony murder is higher than the constitutional standard for imposing the default life without possibility of parole (LWOP) sentence for felony murder.
Keep in mind also that following a jury imposition of the death penalty that this decision will be upheld if any reasonable jury could have found facts sufficient to impose the death penalty by finding some evidence to be credible and other evidence to be less credible, whether or not that was the most plausible interpretation of the facts and whether or not this was actually the reason for the jury's decision.
Also keep in mind that the death qualification of the jury (i.e. striking for cause from the jury pool anyone who is categorically opposed to imposing the death penalty), means that juries in cases where the death penalty is an option are systemically biased in favor of the prosecution in the process of how the judge guilty or innocence, and also, in their evaluation of aggravating and mitigating factors in a case.