A failure to intervene happens when someone with the duty and real chance to stop wrongdoing does nothing.

Each part matters. "Duty" means the person was not just nearby; they had authority, responsibility, or a legal obligation to act. "Real chance" cuts through a common excuse: not every witness is liable, but an officer, supervisor, or government employee who sees excessive force, an unlawful arrest, or another clear rights violation unfolding and has time to step in may be. "Does nothing" can mean staying silent, refusing to report, or standing by while the harm continues. Bad advice often treats misconduct like a one-person problem. It is not. The law can reach the person who let it happen too.

In an injury claim, that can widen who may be held responsible and what evidence matters. Body-camera video, radio traffic, incident reports, and witness statements may show whether there was enough time and authority to act. A civil rights case under 42 U.S.C. § 1983 often includes this theory when one officer allegedly failed to stop another officer's excessive force or other constitutional violation.

In Maryland, these claims usually face the general 3-year civil filing deadline for personal injury actions under Md. Code, Courts and Judicial Proceedings § 5-101. Missing that deadline can sink a strong claim, even where the bystander's silence was obvious.