That's the same as one-party consent (that is, one of the parties having the conversation, not random passersby), which in the US applies federally as well as i

That's the same as one-party consent (that is, one of the parties having the conversation, not random passersby), which in the US applies federally as well as in about 3/4 of the states. But most states - whether one-party or two-party - do not require consent to record a broad swathe of exceptions (particularly extortion, but not just that). Exact laws vary quite a bit - honestly one of the worst things about America is how different laws (of all sorts) can be in different jurisdictions.