(a) At least every ten years and within one hundred twenty days following publication of the results of a decennial census, the legislature shall reapportion the seats in the house of representatives or revise the districts for electing representatives as required by changes in Commonwealth population or by law. A reapportionment or redistricting plan shall provide for contiguous and compact districts and for representation by each member of the house of representatives of approximately the same number of residents to the extent permitted by the separate islands and the distribution of population in the Commonwealth.
(b) If the legislature fails to act pursuant to section 4(a), the governor shall promulgate a reapportionment or redistricting plan within one hundred twenty days after the expiration of the time for the legislature to act. The governor’s plan shall be published in the same manner as an act of the legislature and upon publication shall have the force of law. Upon the petition of any person qualified to vote, the Commonwealth appeals court or the United States District Court if no Commonwealth appeals court has been created under section 3 of article IV has original and exclusive jurisdiction to review a plan and to amend it to comply with the requirements of this Constitution or to establish a plan if the governor has failed to act within the time provided.