"Portions of many of King's speeches were borrowed from other preachers, both fellow African Americans and white radio evangelists. Perhaps most notably, the closing passage from King's famous "I Have a Dream Speech" was borrowed from Archibald Carey, Jr.'s address to the 1952 Republican National Convention. Keith Miller, in Voice of Deliverance: The Language of Martin Luther King, Jr. and Its Sources, argues that such borrowing, which he terms "voice merging," follows in a long tradition of folk preaching, particularly in the African American church, and should not necessarily be termed plagiarism. On the contrary, he views King's skillful combination of language from different sources as a major oratorical skill."
Hmm. Interesting. http://en.wikipedia.org/wiki/Martin_Luther_King%2C_Jr.
If anyone tried plagiarizing king's (albeit poor) work, it'd be termed nothing short of racism and "we gonna git you, sucka!".