While I was waiting for your response, I did some research on Illinois law.

The eavesdropping law in relevant part states:

A person commits eavesdropping when he:

(1) Knowingly and intentionally uses an eavesdropping device for the purpose of hearing or recording all or any part of any conversation or intercepts, retains, or transcribes electronic communication unless he does so (A) with the consent of all of the parties to such conversation or electronic communication or (B) in accordance with Article 108A or Article 108B of the "Code of Criminal Procedure of 1963", approved August 14, 1963, as amended;

That seems to indicate that whenever a party wishes to record a conversation, he must obtain the other party’s consent. It turns out that is not true. The Illinois Supreme Court interpreted the above statute as follows:

The defendant repeatedly refused to produce a driver's license. Defendant was placed in the back of a squad car and subsequently arrested. While waiting for a tow truck, defendant recorded the conversation of two policemen who were seated in the front seat of the car. The policemen testified that they were unaware that defendant was recording their conversation despite the fact that they knew defendant had a tape recorder. The trial court convicted defendant of violating the eavesdropping statute. The appellate court affirmed. This court reversed the appellate court, holding that the eavesdropping statute should not prohibit the recording of a conversation by a party to that conversation or one known by the parties thereto to be present. Beardsley, 115 Ill.2d at 56, 104 Ill.Dec. 789, 503 N.E.2d 346.

We agree with the appellate court's statement Bender v. Board of Fire & Police Commissioners (1989), 183 Ill.App.3d 562, 565, 131 Ill.Dec. 881, 539 N.E.2d 234, that "no eavesdropping occurs where an individual to whom statements are made or directed records them, even without the knowledge or consent of the person making the statements, because the declarant does not intend to keep his statements private vis-a-vis that individual."

The defendant in the present case argues that he had a reasonable belief that the conversation between him and the alleged victim was private. We disagree. As stated above, there can be no expectation of privacy by the declarant where the individual recording the conversation is a party to that conversation. (Beardsley, 115 Ill.2d at 56, 104 Ill.Dec. 789, 503 N.E.2d 346.) We agree with the appellate court's statement Bender v. Board of Fire & Police Commissioners (1989), 183 Ill.App.3d 562, 565, 131 Ill.Dec. 881, 539 N.E.2d 234, that "no eavesdropping occurs where an individual to whom statements are made or directed records them, even without the knowledge or consent of the person making the statements, because the declarant does not intend to keep his statements private vis-a-vis that individual."

In the present case, the alleged victim who was a party to the conversation consented to its recording. This recording enabled the alleged victim to preserve a more accurate record of the conversation. The alleged victim did not listen to or record a conversation she could not otherwise have heard. The statements were not transmitted to another party in violation of section 108A-1 et seq. of the Code of Criminal Procedure of 1963 (Ill.Rev.Stat.1991, ch. 38, par. 108A-1 et seq.). Following Beardsley, we hold that the recording did not violate the Illinois eavesdropping statute, which allows the recording of a conversation by a party to that conversation.

The preceding is from the case People v. Herrington, 645 N.E.2d 957, 163 Ill.2d 507 (Ill., 1994), and it summarizes its earlier holding in People v. Beardsley, 115 Ill.2d 47, 503 N.E.2d 346 (Ill., 1986). In 2001, the Illinois Supreme Court affirmed its prior rulings in the case People v. Edwards, 745 N.E.2d 1212 (Ill., 2001). The Court stated as follows:

The defendant contends that the calls to the Small residence were recorded in violation of the state eavesdropping statute, section 108A 1 of the Code of Criminal Procedure of 1963 (Ill. Rev. Stat. 1985, ch. 38, par. 108A 1). On direct appeal, this court found that the defendant's objection to the introduction of the evidence was waived by his failure to raise the issue in the trial court. Edwards, 144 Ill. 2d at 163-64. The defendant now argues that counsel was ineffective for failing to properly preserve the question.

We do not agree with the defendant that the calls were recorded in violation of the statute. People v. Beardsley, 115 Ill. 2d 47 (1986), and People v. Herrington, 163 Ill. 2d 507 (1994), this court determined that authorization is not required under that provision when recordings are made with the consent of one of the persons taking part in the conversation. In the present case, the calls were recorded with Nancy Small's consent. Thus, we must conclude that no statutory violation occurred in these circumstances. Counsel cannot be considered ineffective for failing to make or pursue what would have been a meritless objection.

So it seems that the general rule in Illinois is that a person may record a conversation without the other’s consent if he is a party to the conversation, or he is present for the conversation. The statute seems to merely prohibit the non-consensual recording of a conversation by a person who would not otherwise be expected to hear it. Be aware that transmitting the conversation, rather than recording it, would apparently be illegal, however.