The Constitution of the State of Illinois is the governing document of the state of Illinois. There have been four Illinois Constitutions; the fourth and current version was adopted in 1970. The current constitution is referred to as the "Constitution of Illinois of 1970" or less formally as the "1970 Constitution." The document is still referred to as the "Constitution of Illinois of 1970" even though there have been amendments to it after 1970. Important features of the 1970 Constitution include the creation of home rule powers for larger municipalities and other units of local government.

The 1970 Constitution has a preamble and 14 articles.

The preamble of the 1970 Constitution is as follows:

We, the People of the State of Illinois—grateful to Almighty God for the civil, political and religious liberty which He has permitted us to enjoy and seeking His blessing upon our endeavors—in order to provide for the health, safety and welfare of the people; maintain a representative and orderly government; eliminate poverty and inequality; assure legal, social and economic justice; provide opportunity for the fullest development of the individual; insure domestic tranquility; provide for the common defense; and secure the blessings of freedom and liberty to ourselves and our posterity—do ordain and establish this Constitution for the State of Illinois.^[1]

The bill of rights and contains similar provisions as the United States Bill of Rights, such as freedom of religion, freedom of speech and freedom of assembly. It also contains items not included in the United States Constitution like section 18, which prohibits discrimination based on sex and section 19, which prohibits discrimination based on physical or mental handicaps.

Describes the division of powers into executive, legislative and judicial branches.

Describes voting qualifications, disqualifications and other election rules. Section 1 stipulates that a person must be 18 years old and a resident of the state for 30 days to vote. Section 4 provides for the Illinois General Assembly to establish rules for elections. Section 5 establishes rules for the state board of election, requiring for no political party to have a majority on the board. Section 7 provides procedures to recall the governor.

Provides rules for the Illinois General Assembly. Section 1 divides the assembly into two bodies, the Illinois Senate with 59 legislative districts, and the Illinois House of Representatives, with 118 representative districts. Section 2 describes the composition of the two bodies. Section 3 describes legislative redistricting procedures. Section 9 describes procedures involving executive vetoes of legislation. Section 14 describes impeachment rules, under which Governor Blagojevich was impeached in the House and removed from office after a trial in the Senate.^[2]

Describes rules for the six state elected members, Governor, Lieutenant Governor, Attorney General, Secretary of State, Comptroller, and Treasurer.

Sets up rules for Supreme Court of Illinois, the Illinois Appellate Court, and the circuit or trial courts of Illinois.

Provides rules for county, township, and city governments and provides them with a limited ability to pass ordinances.

Provides for financial matters including obligation of funds, budgeting, spending, and audits.

Provides rules for various forms of taxation and state debt.

Establishes the goal of free schooling through secondary education and creates a state board of education.

Grants each person the "right to a healthful environment." It sets that to be public policy and the duty of individuals to that a healthful environment is maintained.

Sets rules for the state militia: "The State militia consists of all able-bodied persons residing in the State except those exempted by law." It establishes the governor as the commander in chief of the militia and grants authority to use the militia to "enforce the laws, suppress insurrection or repel invasion."

Establishes rules for persons holding public office. Section 5 prohibits reducing the pension benefits of public employees.^[3] Section 7 provides for public transportation and allows the General Assembly to spend money to provide it.

Describes procedures for amending the constitution. Section 1 describes rules for constitutional conventions. This article requires that Illinois voters be asked at least every 20 years if they desire a constitutional convention.^[4] In 1988 the measure failed 900,109 votes for and 2,727,144 against the measure. 1,069,939 other voters chose neither option.^[5] In 2008, there was an effort by citizens to support a convention. Ultimately, the measure was also defeated by a wide margin,^[6] 1,493,203 votes for and 3,062,724 against from a total of 5,539,172 votes cast. 983,245 voters chose neither option.^[7]

(Source: Southwestern Illinois College. Constitution study Guide. The Illinois Constitution.)

When statehood for Illinois was approved on April 18, 1818, the U.S. Congress approved the formation of a state constitution. An election for delegates to a state constitutional convention was scheduled for July 6, 1818. All white male U.S. citizens who had resided in the Illinois Territory for at least six months prior to the election, or whom were otherwise qualified to vote for representation, were permitted to vote. The main topics of the election were whether it was sensible to have a constitution at that time and, if so, whether to form it and how to select appropriate representatives to frame it. Madison, St. Clair, and Gallatin counties were allocated three delegates each, while all other counties were allocated two delegates each.^[8]

Delegates elected were to attend a meeting at Kaskaskia on August 3. Any record of this election has been lost and it is uncertain where the subsequent meeting was held. However, John Reynolds later noted that the meeting was largely peaceful although there were questions about how to handle slavery.^[8]

Succeeding constitutions were ratified in 1848, 1870 and 1970.^[9]

In 1862 a constitutional convention was held, but the changes known as the "Copperhead constitution" were not ratified by the voters.^[10] Thomas J. Turner and Tazewell B. Tanner were delegates to an 1863 Illinois constitutional convention. A constitutional convention was held in 1920, but in 1922 the changes were rejected by voters.^[11]

The Sixth Illinois Constitutional Convention convened on December 8, 1969 and concluded on September 3, 1970.^[12] The resulting fourth version of the Illinois Constitution was ratified by special election on December 15, 1970,^[13] and went into effect on July 1, 1971.^[14] However, some provisions, such as the change in the dates for the election of constitutional officers, did not take effect for several years.^[15] Important features of the fourth Illinois Constitution include the creation of home rule powers for larger municipalities and other units of local government.

• Law of Illinois

• Illinois Constitution
• Understanding the Illinois Constitution, Illinois State Bar Association.
• Juriga, Mindy (2007). "The Role of Political Parties in Illinois During the 1862 Illinois Constitutional Convention".