The Free Dictionary defines strong arm robbery as taking or stealing something from a person using force or threats but without using a weapon. Use of any weapon when committing a robbery, even if only used to threaten, is considered armed robbery.
The Free Dictionary explains that robbery is a type of larceny, or stealing. Robbery differs from general larceny in that goods are taken from individuals in their presence by force or intimidation, and strong arm robbery is always treated as a more serious crime than basic larceny. If a weapon is used, the crime is considered armed robbery. If no weapon is used, it is strong arm robbery.
If a purse snatcher sneaks up behind a victim and grabs the victim's purse before the victim has a chance to react, it does not count as strong arm robbery since the victim was neither threatened nor attacked physically, as explained by the Free Dictionary. If a purse snatcher enters the victim's personal space and shouts, "Give me your purse!", that constitutes strong arm robbery even though the robber never laid a hand upon the victim. The Free Dictionary explains that this constitutes intimidation and an implied physical threat if the demand is not followed.