Section 5. Said committee shall establish, supervise and maintain a system for the appointment or assignment of counsel at any stage of a proceeding, either criminal or noncriminal in nature, provided, however, that the laws of the commonwealth or the rules of the supreme judicial court require that a person in such proceeding be represented by counsel; and, provided further, that such person is unable to obtain counsel by reason of his indigency. The committee may also establish a system for the provision of counsel in any pre-arraignment procedure. A justice or associate justice shall assign a case to the committee, as hereafter provided, after receiving from the probation officer a written report containing the probation officer’s opinion as to the defendant’s ability to pay for counsel, based on the standards and procedures provided for in section two.