> Well, calling Claude a "third-party communique" here is the stretch.

Why? The privacy policy explicitly says that when you're using it, you're sending your data to Anthropic.

> Say a person used Excel via Office 365 to run some calculations to be given to their lawyer for their defense. Is that considered to be "communicating with a third party?" I don't think so, it's just a computer tool.

Very possibly, actually. At the very least, I wouldn't assume that it's okay to do that without first consulting with a lawyer. I do know of at least one feature in Office (desktop, not the web version) that prompted lawyers to say "if you don't roll this back, we cannot legally use your product anymore and maintain attorney-client privilege." It depends a lot on the actual contractual agreements in the terms of service and privacy policy, and while I know most people don't read them, those things actually matter!