States deal with many policy issues outside the federal government's jurisdiction, so it would surprise no one if Illinois' state constitution differed significantly from its U.S. counterpart. Given that the U.S. Constitution dates from 1787, while voters approved the Illinois Constitution in 1970, you'd expect to see nearly 200 years of historical development reflected in the state charter...yet the logic and language of the Illinois Constitution borrows heavily from the U.S. Constitution. Despite their differences, the two charters share several common features.
Both constitutions' preambles begin with the words "We, the People," and both seek to "insure domestic tranquility" and "provide for the common defense" so as to "secure the blessings of freedom and liberty to ourselves and our posterity."
The Illinois preamble goes further in its ambition, seeking to "provide for the health, safety and welfare of the people," to "eliminate poverty and inequality," and to "assure legal, social and economic justice."
Bills of Rights
Both the federal and Illinois constitutions guarantee protections for certain fundamental rights, including the rights to freedom of speech, religion, assembly and petition. Both also protect against unreasonable searches and seizures and the quartering of soldiers.
The bills of rights do differ in some respects. Illinois borrows from another founding American document, the Declaration of Independence, in affirming inalienable rights to "life, liberty and the pursuit of happiness." The state also guarantees rights that appear nowhere in the text of the U.S. Constitution, such as the right to privacy and non-discrimination on the basis of sex or disability.
Division of Powers
Both constitutions also set out a formal division of powers between the legislative, executive and judicial branches of government. Like the Congress described by the U.S. Constitution, the Illinois Constitution provides for a bicameral General Assembly with a Senate and House of Representatives. Illinois senators serve four-year terms, while U.S. senators are elected for six years.
The impeachment process in Illinois mirrors the U.S. process; only the House of Representatives can bring charges against executive officials or state judges, and only the Senate can try impeached officials. Just as the Chief Justice of the U.S. Supreme Court presides over presidential impeachments, the Chief Justice of the Illinois Supreme Court presides over an impeachment trial of a sitting governor.
Both constitutions provide for changes to the documents by allowing the legislature to call constitutional conventions to consider amendments or propose them. The amendment processes do differ in important ways. Under the U.S. Constitution, two-thirds of both the House and Senate may propose an amendment, or two-thirds of state legislatures may require the Congress to call a constitutional convention to consider changes. In either case, three-quarter of states or conventions must ratify amendments for them to become part of the U.S. Constitution.
In Illinois, voters have a key role in the amendment process. Three-fifths of the General Assembly can propose a constitutional convention to consider amendments, but voters must ratify any changes. The General Assembly can also approve amendments by a three-fifths vote, but voters must ratify those before they take effect, and a petition signed by a certain proportion of voters can force a public vote on amendments to the structure and procedure of the General Assembly.