[maxerickson]

The US constitution doesn't say much about privacy.

The 4th amendment restricts the government from doing things that would (in part) violate privacy of individuals, but it doesn't say much about what other citizens can do in public places.

[colejohnson66]

You're right about the Consitution. However, the law isn't restricted to the Legislative Branch. Case law is law too, and the courts have ruled repeatedly that you have no expectation of privacy in public.