The ruling was narrow, and CBS and the King estate settled the case before the lower court could reconsider, leaving the copyright of the speech in a somewhat confusing legal situation. A CBS press release dated July 12, 2000, discusses the agreement that allowed the network to "retain the right to use its footage of the speeches" from the march and license it to others in exchange for an undisclosed contribution to the Martin Luther King, Jr., Center for Nonviolent Social Change.

In 2009, EMI Publishing cut a deal with the King estate to help ensure that the speech was "accorded the same protection and same right for compensation as other copyrights." EMI was sold in 2011 to a consortium headed by Sony. The King Center did not respond to requests for comment.

The result is that viewing the whole speech online may remain difficult until 2038, when the current copyright expires, because of laws that protect intellectual property long after the author is deceased.

"These expiration dates are incredibly complicated and constantly changing," said David Sunshine, an intellectual-property lawyer with Cozen O'Connor. "Congress always moves the goalposts on these things when lobbying groups come in."

The Copyright Term Extension Act, passed in 1998, and more commonly known as the Sonny Bono Act or Mickey Mouse Protection Act, did exactly that. Worried about its expiring copyrights on early Mickey Mouse productions, the Walt Disney Company helped spur Congress to stretch the length of copyright protection from the life of the author plus 50 years to life plus 70 years. King was killed in 1968, which means the copyright on his Dream speech won't expire until 2038.

So will King's dream be heard the day of his anniversary? That depends on where you want to view it--and how much of it you want to see. Much of what is available shows only fragments of the speech. Some, like the History Channel, note that copyright prevents the presentation of a full version.

Networks and other news organizations can air segments of the speech under the doctrine of "fair use," because they can justify it as substantially newsworthy, Sunshine said. (CBS aired short excerpts this past weekend on its Sunday Morning news show.) But airing the entire speech--all 17 minutes--could blur those lines.

"The less you play, the easier it is to argue it's fair use, generally speaking," Sunshine said. And networks such as CBS are probably more inclined to pay the licensing fee than to shell out hundreds of thousands of dollars to test the waters on a fair-use claim. This creates a noticeable divide between television corporations that could afford to legally challenge the copyright protections (but may not want to, because they do not need to show the full speech) and others, who lack means to challenge that restriction, Sunshine said.