“In the United States, though power corrupts, the expectation of power paralyzes.”

As quoted in Quotations for Our Time (1977), by Laurence J. Peter, p. 509
1970s

Letter http://oll.libertyfund.org/index.php?option=com_content&task=view&id=1407&Itemid=283 to Mandell Creighton (5 April 1887), published in Historical Essays and Studies, by John Emerich Edward Dalberg-Acton (1907), edited by John Neville Figgis and Reginald Vere Laurence, Appendix, p. 504; also in Essays on Freedom and Power (1972)
Paraphrased variant: All power tends to corrupt and absolute power corrupts absolutely.
Context: I cannot accept your canon that we are to judge Pope and King unlike other men, with a favorable presumption that they did no wrong. If there is any presumption it is the other way against holders of power, increasing as the power increases. Historic responsibility has to make up for the want of legal responsibility. Power tends to corrupt and absolute power corrupts absolutely. Great men are almost always bad men, even when they exercise influence and not authority: still more when you superadd the tendency or the certainty of corruption by authority. There is no worse heresy than that the office sanctifies the holder of it. That is the point at which the negation of Catholicism and the negation of Liberalism meet and keep high festival, and the end learns to justify the means.

Nadia Chernyshevski
Green Mars (1993)

17 U.S. (4 Wheaton) 316, 406-407
McCulloch v. Maryland (1819)
Context: [T]he Government of the Union, though limited in its powers, is supreme within its sphere of action. This would seem to result necessarily from its nature. It is the Government of all; its powers are delegated by all; it represents all, and acts for all. Though any one State may be willing to control its operations, no State is willing to allow others to control them. The nation, on those subjects on which it can act, must necessarily bind its component parts. But this question is not left to mere reason; the people have, in express terms, decided it by saying, [p406] "this Constitution, and the laws of the United States, which shall be made in pursuance thereof," "shall be the supreme law of the land," and by requiring that the members of the State legislatures and the officers of the executive and judicial departments of the States shall take the oath of fidelity to it. The Government of the United States, then, though limited in its powers, is supreme, and its laws, when made in pursuance of the Constitution, form the supreme law of the land, "anything in the Constitution or laws of any State to the contrary notwithstanding."

Source: Freedom from Fear (1991)
Context: It is not power that corrupts but fear. Fear of losing power corrupts those who wield it and fear of the scourge of power corrupts those who are subject to it. Most Burmese are familiar with the four a-gati, the four kinds of corruption. Chanda-gati, corruption induced by desire, is deviation from the right path in pursuit of bribes or for the sake of those one loves. Dosa-gati is taking the wrong path to spite those against whom one bears ill will, and moga-gati is aberration due to ignorance. But perhaps the worst of the four is bhaya-gati, for not only does bhaya, fear, stifle and slowly destroy all sense of right and wrong, it so often lies at the root of the other three kinds of corruption. Just as chanda-gati, when not the result of sheer avarice, can be caused by fear of want or fear of losing the goodwill of those one loves, so fear of being surpassed, humiliated or injured in some way can provide the impetus for ill will. And it would be difficult to dispel ignorance unless there is freedom to pursue the truth unfettered by fear. With so close a relationship between fear and corruption it is little wonder that in any society where fear is rife corruption in all forms becomes deeply entrenched.

The Short Reign of Pippin IV (1957), p. 102