The Illinois Supreme Court announced this week that it has adopted new and revised rules of professional conduct for lawyers licensed to practice in the state, adding guidelines on Web advertising, the sale of a firm, and even sex with clients.

A significant change in the new rules, which take effect on Jan. 1, is that they will now be accompanied by commentary to explain the purpose and provide an interpretation of each rule, though only the text of the rule is legally binding. Lawyers risk disciplinary action if they violate the rules.

The 120-page preamble, rules and commentary was written over the past seven years, with input from lawyers, judges and law professors, and adopted by the Supreme Court, after revisions, during a private May session. The new code, the state’s first complete revision since 1990 after an initial adoption in 1980, are largely based on additions to the American Bar Association’s model rules in 2002 and 2003, though some of the rules are unique to Illinois, the court said in a press release.

New rules define the manner in which a lawyer can act as a mediator or arbitrator, spell out a lawyer’s duties to a prospective client in preliminary discussions before a formal relationship is cemented, and address how a lawyer should respond on receiving a document inadvertently.

And the code for the first time adopted the ABA directive that prohibits a lawyer from having sexual relations with a client unless a prior relationship existed. It also spells out rules for lawyers and firms advertising online and eliminates some restrictions on reasons for selling a law firm.

The code maintains a stricter rule than the ABA with respect to lawyers’ responsibility to report misconduct by other lawyers, said Jim Grogan, who is chief counsel for the Illinois Attorney Registration and Disciplinary Commission.

Holland & Knight attorney Richard Redmond, McDermott, Will & Emery attorney Steven Pflaum, Northwestern Law School adjunct professor Robert Creamer, and Schiff Hardin attorney Thomas Luning all played key roles in collecting input for and crafting the new rules.

Lynne Marek can be reached at [email protected].