R.I. Gen. Laws § 12-16-11: Exemption from process of witnesses passing through state.

A person passing through this state while going to another state in obedience to a summons or order to attend and testify in that state or while returning from testifying, shall not, while so passing through this state, be subject to arrest or the service of process, civil or criminal, in connection with matters which arose before his or her entrance into this state under the summons or order.