A jacket-shaped restraint that's meant to confine a violent person safely is called a straitjacket. Straitjackets were once commonly used in psychiatric hospitals.
These days you're much more likely to see a straitjacket used as a prop in magic show than in a hospital. Illusionists use straitjackets to perform escape tricks, since they're famously difficult (if not impossible) to wriggle out of. Straitjackets are made of sturdy material and hold the wearer's arms tightly against the body. Before the invention of modern psychiatric medicines and techniques, mentally ill patients were frequently restrained in straitjackets to protect themselves and others.