R.I. Gen. Laws § 12-16.1-8: Exemption from arrest and service of process.

If a witness from another state comes into or passes through this state under an order directing the witness to attend in this or another state, he or she shall not, while in this state pursuant to the order, be subject to arrest or the service of process, civil or criminal, because of any act committed prior to his or her arrival in this state under the order.