R.I. Gen. Laws § 12-16-10: Exemption from process of witnesses entering state.

If a person comes into this state in obedience to a summons directing him or her to attend and testify in this state that person shall not, while in this state pursuant to the summons or order, 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.