Final answer:
The U.S. Supreme Court case that held mandatory death sentences in cases of first-degree murder were unconstitutional was Woodson v. North Carolina in 1976.
Step-by-step explanation:
The U.S. Supreme Court case that held that mandatory death sentences in cases of first-degree murder were unconstitutional because they did not allow for a jury to weigh in on the aggravating and mitigating factors when making a sentence recommendation was Woodson v. North Carolina. This case was decided in 1976. The Court held that the imposition of the death penalty must be tailored to the particular circumstances of the individual defendant and the crime committed.
Learn more about Unconstitutionality of mandatory death sentences in first-degree murder cases