You do NOT have any 'right' in law/regulations to transmit on a frequency you are not licensed to transmit on. The regulation often quoted applies only to ham stations being allowed to transmit on any HAM frequency in emergencies, even if the operator does not normally have priviledges to transmit on those ham frequencies.
That is not correct. The applicable regulations are found in
47 CFR 97.403 and 97.405. They read as follows (emphasis added):
97.403. No provision of these rules prevents the use by an amateur station of any means of radio communication at its disposal to provide essential communication needs in connection with the immediate safety of human life and immediate protection of property when normal communication systems are not available.
97.405. (a) No provision of these rules prevents the use by an amateur station in distress of any means at its disposal to attract attention, make known its con dition and location, and obtain assistance.
(b) No provision of these rules prevents the use by a station, in the exceptional circumstances described in paragraph (a) of this section, of any means of radio communications at its disposal to assist a station in distress.
There are some who believe these provisions still limit the amateur radio operator to the amateur band, but that's probably because they don't know about
47 CFR 97.111(a)(2) which reads:
97.111(a) An amateur station may transmit the following types of two-way communications:
. . .
(2) Transmissions necessary to exchange messages with a station in another FCC-regulated service while providing emergency communications;
So there you have it. 47 CFR 97.111(a)(2) bestows an amateur station the authority to make the "transmissions necessary to exchange messages with a station in another FCC-regulated service while providing emergency communications." 47 CFR 97.403 and 47 CFR 97.405 define what constitutes an emergency.
In any case, 97.403 and 97.405 specifically state that no part of this (part 97) rule applies in those emergency cases. That means that even without 97.111, the rules limiting amateurs to specific frequencies in 97.301 are not applicable during the emergency situations described in 97.403 and 97.405.
The FCC has always been very clear that one of the primary missions of amateur radio is emergency communications. It seems strange that so many would interpret the rules in a way that contradicts common sense and the very intent of the FCC in establishing the amateur service in the first place.
Will you get in trouble if you hop on to a local police channel to report a crime in progress when you could have used you cell phone? You bet. Will you get in trouble if you hop on to a local police channel to report a man with a gun shooting at people in the park when you have no cell phone and no other immediate means of communication? Probably not. Even if the rules didn't allow it in any way shape or form, would you really decide that saving yourself some trouble with the FCC was worth people's lives? I doubt it.