Constitution of the State of Illinois Art. IV, § 3. Legislative Redistricting

(a) Legislative Districts shall be compact, contiguous and substantially equal in population. Representative Districts shall be compact, contiguous, and substantially equal in population.

(b) In the year following each Federal decennial census year, the General Assembly by law shall redistrict the Legislative Districts and the Representative Districts.

If no redistricting plan becomes effective by June 30 of that year, a Legislative Redistricting Commission shall be constituted not later than July 10. The Commission shall consist of eight members, no more than four of whom shall be members of the same political party.

The Speaker and Minority Leader of the House of Representatives shall each appoint to the Commission one Representative and one person who is not a member of the General Assembly. The President and Minority Leader of the Senate shall each appoint to the Commission one Senator and one person who is not a member of the General Assembly.

The members shall be certified to the Secretary of State by the appointing authorities. A vacancy on the Commission shall be filled within five days by the authority that made the original appointment. A Chairman and Vice Chairman shall be chosen by a majority of all members of the Commission.

Not later than August 10, the Commission shall file with the Secretary of State a redistricting plan approved by at least five members.

If the Commission fails to file an approved redistricting plan, the Supreme Court shall submit the names of two persons, not of the same political party, to the Secretary of State not later than September 1.

Not later than September 5, the Secretary of State publicly shall draw by random selection the name of one of the two persons to serve as the ninth member of the Commission.

Not later than October 5, the Commission shall file with the Secretary of State a redistricting plan approved by at least five members.

An approved redistricting plan filed with the Secretary of State shall be presumed valid, shall have the force and effect of law and shall be published promptly by the Secretary of State.

The Supreme Court shall have original and exclusive jurisdiction over actions concerning redistricting the House and Senate, which shall be initiated in the name of the People of the State by the Attorney General.