05/27/2026
LAW WITH JONAH SANDERS — THE IMPOSSIBILITY‑OF‑A‑CRIME DEFENSE & THE FAILURE‑TO‑PRESENT‑AN‑ALIBI DOCTRINE:
In criminal law, a person cannot be convicted of a crime that was legally impossible to commit, because the Constitution requires both a guilty act and a guilty mind, and when the law itself does not criminalize the conduct, the offense collapses. Courts have repeatedly held that legal impossibility is a complete defense, meaning that even if the defendant believed they were committing a crime, the act still cannot be punished if the statute does not prohibit it. This principle is rooted in the Due Process Clause, which forbids conviction without a legally valid offense, and is supported by cases such as People v. Jaffe, 185 N.Y. 497 (1906), where the court held that a defendant cannot be guilty of receiving stolen property when the property was not actually stolen, making the crime legally impossible. But impossibility becomes even more powerful when combined with another constitutional violation: the failure of counsel to present a valid alibi. The U.S. Supreme Court has made clear that the Sixth Amendment guarantees not just the presence of counsel, but effective assistance, and when an attorney fails to investigate or present an alibi that would have proven the defendant was not at the scene, courts treat it as a structural breakdown in the adversarial process. In Strickland v. Washington, 466 U.S. 668 (1984), the Court held that counsel’s performance is constitutionally deficient when it falls below an objective standard of reasonableness and prejudices the defense. Later cases applied this directly to alibi failures: in Grooms v. Solem, 923 F.2d 88 (8th Cir. 1991), the court reversed a conviction because counsel failed to investigate and present alibi witnesses; in Montgomery v. Petersen, 846 F.2d 407 (7th Cir. 1988), the court held that ignoring a credible alibi is ineffective assistance as a matter of law; and in Bigelow v. Haviland, 576 F.3d 284 (6th Cir. 2009), the court ruled that failing to call an alibi witness who would have placed the defendant elsewhere violated the Sixth Amendment. When you combine these doctrines, the law becomes crystal clear: a defendant cannot be convicted of a crime that was legally impossible to commit, and counsel cannot constitutionally allow a conviction to stand when an alibi proves the defendant could not have committed the act. The impossibility defense protects against criminalizing non‑criminal conduct, and the alibi doctrine protects against convicting the wrong person. Together, they form one of the strongest constitutional shields in criminal law, ensuring that no person is punished for an act that either was not a crime or was not committed by them.
