Section 129D. For the satisfactory conduct of a prisoner while confined at a correctional institution of the commonwealth, or any jail or house of correction, but working at a state hospital or state school, satisfactory completion of an educational program leading to the award of a high school equivalency certificate, satisfactory performance of said prisoner in completion of any other educational sequence or any vocational training program established within or without the institution, satisfactory performance of said inmate when he is employed on work-release or in a prison industry, or satisfactory performance of said inmates in any other program or activity which the superintendent of the institution shall deem valuable to said prisoner's rehabilitation, the commissioner may grant, in addition to the deductions of sentence provided under sections one hundred and twenty-nine and one hundred and twenty-nine C, a further deduction of sentence of not more than 5 days per program or activity for each month while said prisoner is working in a state hospital or school, on work-release or working in a prison industry, or partaking in any of the said programs or activities as aforesaid; provided, however, that in no event shall said deductions exceed a maximum monthly total of 10 days. For a prisoner's successful completion of a program or activity requiring 6 months of satisfactory participation, as designated by the commissioner, the commissioner may grant an additional deduction of sentence of up to 10 days, to be deducted in the month during which successful completion of the designated program or activity is achieved. Such further deduction of sentence shall be added to any deduction to which the prisoner is entitled under said section 129C for reducing the term of imprisonment by deduction from the maximum term for which the prisoner may be held under the prisoner's sentence or sentences, and for reducing from the minimum term of the sentence or sentences the good conduct credits earned under this section for parole eligibility as provided under section 133. No prisoner shall be eligible for a reduced sentence under this section unless they have satisfied both the requirements of the program or activity and demonstrated competency in the material, as determined by the commissioner.
A prisoner whose term of imprisonment is reduced from the maximum term for which he may be held under his sentence or sentences shall receive from the commissioner a certificate of discharge on the date which has been determined by such additional deductions from the maximum term of his sentence or sentences.
Good conduct credit earned or to be earned under this section or section 129C shall be subject to reduction by order of the court upon a finding that a claim or action brought by a prisoner was frivolous and filed in bad faith in order to abuse the judicial process or upon a determination that an inmate intentionally and in bad faith in order to abuse the judicial process has misrepresented or omitted material information in an affidavit submitted under section 29 of chapter 261.