Rights: natural or instituted?

The state of nature is no licence: it is governed by a law of nature that reason discovers. Since all men are the workmanship of one Maker, sent into the world by his order and about his business, none has the right to destroy another or to put him under his absolute power. From this original equality Locke derives, not a mere duty not to harm, but correlative subjective rights, to life, liberty and estate, that each bears prior to any government. Power is therefore legitimate only to secure them; to violate them makes it tyrannical. These "unalienable rights" would pass almost word for word into the American Declaration of Independence.

Second Treatise of Government, II-V

The principle of utility holds for all people and all times: the criterion of pleasure and pain is a universal natural fact, and the calculus applies the same way everywhere. Bentham does not relativize morality to cultures nor reduce it to mere convention; this is a naturalistic universalism, grounded in a sentience common to all beings.

An Introduction to the Principles of Morals and Legislation, ch. I-IV (the principle and its measure, universally valid)

A right, for Bentham, is nothing but the benefit of an obligation that the law lays on others and backs by a sanction: no positive law, no obligation, hence no right. Natural rights prior to any law are therefore a contradiction in terms, a wish dressed up as a legal fact, and even a danger, since to invoke an imprescriptible right against the law opens the door to anarchy. The rejection is not nihilist but utilitarian: there are indeed rights, but it is utility, not nature, that should guide the legislator in creating them.

Anarchical Fallacies; Introduction to the Principles of Morals and Legislation