Under what conditions can a private person make a lawful arrest in Massachusetts?

In Massachusetts, a private person may lawfully arrest an individual if they have probable cause to believe that a felony has been committed. Probable cause is a legal standard that requires that the private individual has sufficient reasonable grounds to suspect that someone has committed a crime. This threshold is important because it helps balance the rights of the individual being arrested and the ability of citizens to act when they believe a crime has occurred.

In this context, having probable cause allows a private citizen to take immediate action, such as detaining the suspect until law enforcement can take over. This principle is rooted in the common law tradition, which grants individuals the right to intervene in preventing crime. This option reflects the legal understanding that the arrest should not be arbitrary or based on mere suspicion but must be grounded in a reasonable belief based on observable facts.

The other options deviate from this standard. Apprehending someone without evidence or with only a suspicion does not meet the legal requirement for a lawful arrest, and the need for the victim's consent or knowledge of the suspect being a known criminal does not determine the legality of a private arrest in Massachusetts. Thus, the requirement of having probable cause for a felony appropriately encapsulates the conditions under which a private person may conduct a lawful arrest.