MBE Rules · Criminal Law
Omission Liability
Omission as actus reus
The rule
Failure to act is criminal only with a legal duty — statute, status relationship, contract, voluntary assumption plus seclusion, or creation of peril — plus knowledge and ability to act.
In plain English
Omission liability means that a person can be held criminally responsible for failing to act only if they have a legal duty to act. This duty can arise from statutes, relationships, contracts, or situations where they have voluntarily assumed responsibility and isolated the person in danger, along with having the knowledge and ability to act.
Worked example
A lifeguard at a pool sees a child struggling to swim but does not jump in to help. The lifeguard has a legal duty to act due to their employment, knows the child is in danger, and is physically able to rescue them. Because of this, the lifeguard could be held criminally liable for their failure to act.
Memory hook
Duty to act means you can't just sit back when you're responsible!
The trap
Exams often present scenarios where students might confuse moral obligations with legal duties, leading them to incorrectly assume liability without a clear legal duty. Students may also overlook the requirement of knowledge and ability to act.
How examiners test it
Questions typically involve fact patterns where a person fails to act in a situation that raises questions about their legal duty, often including elements that test the student's understanding of the specific duties that create liability.
Drill this rule until it can't fail you.
Vrenberg generates unlimited questions on this exact rule, tracks your mastery of it, and brings it back until it sticks.