In the USA (and most other jurisdictions, really) as soon as you write it down, you have the copyright on it. You also have some control over "derivative works" including any copies of the "performance" of the speech. In music, for example, you would need to pay royalties to the songwriter for publicly playing a recording of their song, no matter who actually sang the song.
I'm kind of surprised congress didn't try to retroactively copyright the Declaration of Independence and Gettysburg Address and force textbook publishers to pay royalties.
Laws are protected by copyright and documents incorporated by reference into the law may be placed online.
The model building codes which are both incorporated by reference into many laws and are protected by copyright as model building codes, provided the test case.
Those were works made by the government, so they're automatically in the public domain. I don't see why you're against Mr. King having the copyright on the speech he wrote and gave?
USA was just about the last place to accede to the international treaties on copyright, wherein copyright is granted at the time of creation of 'a work'. You don't have to fix the work in any particular medium to gain copyright - an expressive, creative mime could be a copyright work; or just a tune you whistled, or a cake, or ...
