Both concurrent (section 51) and exclusive (section 52) powers are stated to be "subject to this Constitution". As a result, the Commonwealth's law-making power is subject to the limitations and guarantees in the Constitution (both express and implied). For example, section 99 forbids the Commonwealth from giving preference to any State or part of a State "by any law or regulation of trade, commerce, or revenue". And as discussed below, an implied guarantee of freedom of political communication has been held to limit the Commonwealth's power to regulate political discourse.