Almost all courts confronted with the issue have decided that the First Amendment gives you the right to record an officer in public while he is performing his duties. But laws in some places prohibit people from recording officers surreptitiously (or secretly).
(For more about the right to record, and for more on its limitations, see Recording the Police: Legal? To learn about lawsuits against police related to recording activities, see Can you sue the police if they stop you from recording them?)
Whether the conversation the officer is having is the kind of “private” oral communication that would trigger a state’s wiretapping, electronic surveillance, or eavesdropping laws depends on the situation, and on the courts’ interpretation of the relevant law.
“Private" generally conveys that the conversation is intended only for those involved in the conversation or who hold a confidential relationship with the speaker, or that the conversation is otherwise not open or in public. On the other hand, the fact that communications are made in public doesn’t necessarily mean they aren’t private. (State v. Flora, 68 Wash. App. 802 (Div. 1 1992).)
The following are situations where a court found that a law enforcement officer didn’t have a reasonable expectation that his conversation was private. As such, the citizen’s recording didn’t constitute a crime under the relevant wiretapping, surveillance, or eavesdropping law.
Whether you may lawfully record the police depends on the circumstances and the law in your jurisdiction. One court might find that it was legal to secretly record the police under a particular set of facts, while another might come to a different conclusion. If you plan to record officers, you may want to consult a lawyer. Certainly do so if you’ve been arrested or prosecuted, even if not for recording. A knowledgeable lawyer will be able to explain your jurisdiction’s laws, give you advice, and protect your rights.