Commonwealth v. Boutwell was a United States Supreme Court case that dealt with the issue of whether a state could be held liable for damages caused by a state officer acting in his official capacity. The case arose when the plaintiff, Boutwell, sued the Commonwealth of Massachusetts for damages caused by a state officer who had arrested him without a warrant. The Supreme Court held that the Commonwealth could be held liable for the damages caused by the officer, as the officer was acting in his official capacity and the Commonwealth was responsible for his actions. The Court also held that the state could not be held liable for the officer's negligence, as the officer was acting in good faith and in accordance with the law. The Court further held that the state could not be held liable for the officer's malicious intent, as the officer was acting in his official capacity and the Commonwealth was not responsible for his actions. The Court's decision established that a state can be held liable for damages caused by its officers acting in their official capacity.

In Commonwealth v. Boutwell, the Supreme Court was asked to decide whether a defendant could be convicted of manslaughter for killing another person in self-defense when they were not aware that their actions would result in death. The majority opinion held that the defendant should be found guilty because he had acted with conscious disregard for human life and thus his actions constituted manslaughter. However, Justice Field dissented from this decision, arguing that it was unfair to convict someone who did not know or intend to cause death as a result of their action. He argued that if the law required such knowledge then it would lead people into taking extreme measures out of fear of being prosecuted even though they may have been acting in self-defense without any intention to kill anyone. Furthermore, he noted that there is no evidence suggesting the defendant knew his act would lead to death and therefore conviction on these grounds was unjustified under existing laws at the time.