Ill. Sup. Ct. R. 3.1
A lawyer shall not bring or defend a proceeding, or assert or controvert an issue therein, unless there is a basis in law and fact for doing so that is not frivolous, which includes a good-faith argument for an extension, modification or reversal of existing law. A lawyer for the defendant in a criminal proceeding, or the respondent in a proceeding that could result in incarceration, may nevertheless so defend the proceeding as to require that every element of the case be established.
Ill. Sup. Ct. R. 3.1
Comment
[1] The advocate has a duty to use legal procedure for the fullest benefit of the client's cause, but also a duty not to abuse legal procedure. The law, both procedural and substantive, establishes the limits within which an advocate may proceed. However, the law is not always clear and never is static. Accordingly, in determining the proper scope of advocacy, account must be taken of the law's ambiguities and potential for change.
[2] The filing of an action or defense or similar action taken for a client is not frivolous merely because the facts have not first been fully substantiated or because the lawyer expects to develop vital evidence only by discovery. What is required of lawyers, however, is that they inform themselves about the facts of their clients' cases and the applicable law and determine that they can make good-faith arguments in support of their clients' positions. Such action is not frivolous even though the lawyer believes that the client's position ultimately will not prevail. The action is frivolous, however, if the lawyer is unable either to make a good-faith argument on the merits of the action taken or to support the action taken by a good-faith argument for an extension, modification or reversal of existing law.
[3] The lawyer's obligations under this Rule are subordinate to federal or state constitutional law that entitles a defendant in a criminal matter to the assistance of counsel in presenting a claim or contention that otherwise would be prohibited by this Rule.