§97.113(a)(4) states:
No amateur station shall transmit [...] obscene or indecent words or language
These are not the same regulations that prohibit TV stations from broadcasting obscene or indecent content. However, the above language applies specifically to amateur radio in its entirety.
The lawTo my knowledge, the U.S. Code does not explicitly state what is "obscene" or "indecent", but the FCC, as the organization is responsible for enforcement, and has issued some guidance, which is in turn based on legal precedent.