Sounds like our Prime Directive. We're not supposed to interfere, either. _{( Bones pauses for a moment, sighs. You can hear air-quotes, the mocking capitalization, of "Prime Directive." )}

Don't think it's ever as cut and dry as we want, and there's probably no rule that's going to save you one hundred percent of the time. But as far as it goes it seems you've got the right idea of it.