Is it legal to record a conversation?

Federal law and the majority of states follow one-party consent, meaning it is lawful to record a conversation as long as one participant, which can be you, consents. Roughly a dozen states, including California, Florida, Illinois, Pennsylvania, and Washington, require consent from all parties, making it a crime to record without everyone's agreement. This is why customer service calls announce recording: the company is obtaining consent to satisfy the strictest applicable rule. Penalties in all-party states can include criminal charges and civil liability, and illegally obtained recordings are often inadmissible in court, which defeats the usual purpose of making one.

Two complications matter in practice. Interstate calls create a conflict of laws, and the safe assumption is that the stricter state's rule applies, so recording a call from a one-party state to someone in California should be treated as requiring their consent. And recording in public differs from recording private conversations: there is generally no expectation of privacy for what can be overheard in a public place, and courts have consistently held that recording police performing their duties in public is protected by the First Amendment, subject to not physically interfering. Video without audio is often treated differently from audio recording, since wiretapping statutes target the audio. Given the variation, announcing that you are recording is the reliable approach, and it usually costs nothing but the awkwardness.