Criminal Law Defenses
Insanity is often the logic of an accurate mind overtasked.
-- Oliver Wendell Holmes
In every criminal trial, the government is constitutionally required to prove its case against the defendant beyond a reasonable doubt. Additionally, defendants in criminal cases have a constitutional right to be free from compelled self-incrimination. Taken together, these concepts mean that in criminal cases, the government must independently investigate, obtain and present evidence against defendants. Criminal defendants are not required to speak or otherwise respond to the government's case against them, and the government shoulders the entire responsibility for proving its case.
Notwithstanding these prosecutorial responsibilities and constitutional protections, many criminal defendants voluntarily choose to present evidence during a criminal trial in response to the government's case. Such evidence might challenge the government's case-in-chief and/or attempt to present an excuse or justification for the defendant's behavior. Evidence challenging the government's case-in-chief will usually seek to demonstrate that the government does not have sufficient evidence to prove one or all of the material elements of the crime (i.e., the act, the mental state, causation and social harm) beyond a reasonable doubt. In challenging the government's case-in-chief, a defendant might also introduce evidence designed to prove that the government has charged the wrong person. This is known as an "alibi" defense, and the defendant will typically present evidence in the