R.I. Gen. Laws § 10-9.1-8: Waiver of or failure to assert claims.

All grounds for relief available to an applicant at the time he or she commences a proceeding under this chapter must be raised in his or her original, or a supplemental or amended, application. Any ground finally adjudicated or not so raised, or knowingly, voluntarily and intelligently waived in the proceeding that resulted in the conviction or sentence or in any other proceeding the applicant has taken to secure relief, may not be the basis for a subsequent application, unless the court finds that in the interest of justice the applicant should be permitted to assert such a ground for relief.