If he intended the speech to be in the public domain, he would have put it in the public domain... either during his life, or via his will. That fact that he didn't says more about his intentions than any of our after-the-fact speculation.
I'm not sure it's exactly a ringing endorsement of the Copyright Act of 1976 that Martin Luther King Jr. didn't take the time out of his civil rights campaign to work out the copyright status of everything he ever said in the less than half a decade between the time he gave this speech and his untimely death.
This sure makes it sound to me like he was more concerned with the civil rights movement of the 1960s than with the copyright status of his speech in 2025.
EDIT: Come on, downvoters — do you really mean to suggest that King would have wanted a civil rights memorial to have to pay out his family before it could celebrate his cause?
My opinion isn't the one that matters. And of course the law would have to apply equally to everyone. We can't make exceptions for speeches we would really like to have in the public domain vs. boring speeches. I don't think the Berne convention is perfect, but generally, I like the idea that "As soon as a work is 'fixed', that is, written or recorded on some physical medium, its author is automatically entitled to all copyrights in the work, and to any derivative works unless and until the author explicitly disclaims them, or until the copyright expires." (wikipedia)
Your question was a non sequitur, quoting a piece of the constitution (which applies to all works made in the US equally) and then asking my opinion about one specific speech. I would say that, now that the speech is made, it would be good to have it in the public domain. But if we put all the speeches in the public domain, professional speechwriters would find it much harder to make a living. So in general, I wouldn't recommend that kind of behavior.
To answer your question, I don't think MLK's speech was either science nor a "useful art" so it wouldn't have an effect either way.
If you don't think the question of benefit to society is relevant to this discussion.... well, that isn't my problem.
"if we put all the speeches in the public domain, professional speechwriters would find it much harder to make a living"
Yeah. If I were to give a public performance of this speech in my public library that would really hurt speechwriters.
I'll give you a hint, it works like this:
Person A needs a speech. They ask Person B to write one.
Person B agrees in exchange for money. They both sign a contract.
Person A receives the speech. Person B gets paid per the contract.
Person A gives the speech.
Person C through Z copy the speech and give it themselves. Nobody cares.
Person A needs a speech. They can't pay person B enough for person B to make a living as a speechwriter. Person A writes themselves a crappy speech that no one wants to copy. The end.
Is that really better than:
Person A needs a speech. Person B writes a speech for them and collects $x royalties when person A gives it, and each time person C-Z (who really liked it) give it. Now everyone gets a good speech, and person B is actually able to write speeches for a living.
The fact that B can't make enough to make a living off of speeches implies to me that speeches might not actually be that valuable.
Why do we need to make it so that B can make a living off of speeches? That's stupid. B has no more claim to make a living off of speeches than I do to make a living writing Python.
The whole reason capitalism is supposed to work is that it properly allocates resources--and if speeches aren't actually worth enough to make a living on, maybe you should do something besides writing speeches.
It's about tragedy of the commons. When each person is looking out for their own interests, they might not think that e.g. filmmakers are worth the millions of dollars it takes to make a movie. Then out society wouldn't have any big-budget movies, and we'd all be worse off. But of they get copyright and can charge theaters for showing the movies, then they can make the movies. And our society in general is better off.
"Then out society wouldn't have any big-budget movies, and we'd all be worse off."
That is quite a leap of logic... Though it is interesting that you use the example of film, considering how often film so often lifts from the public domain.
(from above) Scarcity is the root of all Evil. Copyright increases scarcity.
(conclusion) Copyright begets Evil.
A bit Old-testament, mind you, but I really do believe this to be the case.
You are absolutely correct in the idea that without copyright modern cinema (for example) wouldn't exist.
The problem I have with your example of movies is that there are many assumptions being made that I don't think are reasonable: we don't "need" big-budget movies, society isn't automatically "better off" because of the movies, and the movies don't "need" to cost as much as they do.
If movie production had to be paid for, up front, before being made and put to film, this would be fine. You would bet your ass that "Hollywood Accounting" would disappear, because the margins would be too slim to allow otherwise.
You have a pile of money and expectations that you'll make a movie; if you don't pull it off, you are publicly shamed (thank you Internet!) and never able to raise a cent again. If you do pull it off, you got payed (you did factor in cost of your time in your budget quote, right?) and the people got their movie. If it's pirated it doesn't matter because it was already totally paid for. It's a wonderful thing.
The Great Pyramids of Egypt and the Great Wall of China and the World archipelago in Dubai are all amazing achievements--but would you ever pay for them today with a straight face?
For good measure:
Consider the top 50 most expensive films of all time ( http://en.wikipedia.org/wiki/List_of_most_expensive_films ), and then consider how much money they brought in. The entire system was a "valid allocation" because of copyright guaranteeing a return on investment, whereas otherwise it never would've gotten made ("So, you want me to pay you $20 so in 4 years I get to watch a movie about the Titanic?").
And now think about how many people in the US couldn't afford medical care. Or couldn't afford housing. Or couldn't eat healthily. Or couldn't afford education.
This, while the very society and civilization they've ceded control of their lives to goes to great lengths to ensure the unequal distribution of goods and services! Goods and services that ought to be free to duplicate!
The whole thing is an embarrassment to our species.
I don't mind for a damned second paying for a project, but I most certainly mind subsidizing thugs to beat a captive market while people are suffering.
~
I'm not against movies, art, music, literature, or whatever else. I just think that regulatory capture of modern copyright (and for that matter, patent) law is more trouble than its worth.
At the end of the day, you do realize that the endgame of this all is not being able to tell another human being a story or sing them a song or show them a picture without paying a fee somehow?
Copyright is enforcing the idea that that most noble of pursuits--sharing, alleviating that one great Evil of scarcity for your fellow man--is somehow wrong. It's disgusting.
You really don't need a pre-made license, like one of the Creative Commons licenses. Just grant the use of the speech and recordings of the speech for any purpose. Or make the text of the speech free for noncommercial use.
Just about anybody in recorded history could have created the phonograph. It's a dead simple concept, even the Mesopotamians probably could have managed it, all you need is a needle (probably could be bone), something to scratch lines into with it (wax for instance, maybe the clay they used for tablets), and some sort of diaphragm (leather should work nicely). Just imagine, we could have voice recordings of Alexander the Great, or Gautama Buddha.... that would be fucking wild.
Nobody did it until Edison in the late 19th century. Why? Because the idea of doing something is in most cases more elusive than the ability to do so.
The idea is licensing designed to keep a work free, not licensing designed to restrict. Even if that idea existed at the time, it was not prominent, evidenced by the lack of stock licenses to do so at the time.
Would MLK want people to pay $20 to watch his speech?