Final answer:
Duress cannot be used as a defense in a homicide prosecution due to the requirement of intent and constitutional protections.
Step-by-step explanation:
The defense of duress can never be used in a homicide prosecution due to several legal principles and constitutional protections. One of the key elements in a homicide case is the intent to kill, which is essential to proving the crime. Duress, which is a defense that claims the defendant was forced or coerced into committing the crime, contradicts the requirement of intent. Additionally, the Fifth and Sixth Amendments of the U.S. Constitution protect individuals from being compelled to testify against themselves or being deprived of life, liberty, or property without due process of law, which also prevents the use of duress as a defense in a homicide prosecution.