The Walt Disney Co. is breathing a sigh of relief after a federal judge affirmed its position as the new owner of the Marvel comics universe, including some popular characters like Thor, Spider-Man and the Fantastic Four.

The estate of comic book artists Jack Kirby had sued Marvel and Disney soon after the two announced a $4 billion merger in 2009. Kirby's estate, according to the Los Angeles Times, filed 45 copyright termination notices, demanding the return of every character Kirby is credited of creating between 1958 and 1963.

Marvel, however, contended that Kirby developed the characters in a "work-for-hire" situation. That means any work created while collecting a regular paycheck to make such creations, become the property of the company signing the paychecks, not necessarily the person who actually did the creation.

Kirby, who died in 1994 at the age of 76, worked closely with Stan Lee to create a number of popular characters, including the Fantastic Four in 1961 and later Thor, the Hulk, the original X-Men, and even the Black Panther.

Despite the loss, the Kirby estate said it would fight the ruling, which is based on a century-old copyright law in the United States.

"We respectfully disagree with the court's ruling and intend to appeal this matter to the Second Circuit," the estate said in a statement. "Sometimes you have to lose in order to win. We knew when we took this on that it would not be an easy fight given various arcane and contradictory 'work-for-hire' decisions under the 1909 Copyright Act."

The law is actually not even active on the federal books anymore, being replaced by a new law in 1976. However, it remains enforce for anything created before that law went into effect in 1978, which created the modern rules of copyright law in the country.

One of the biggest changes between the 1909 and 1976 laws were that you no longer were required to attach a copyright notice to a property to get federal copyright protection. Now just proving that such a work has been published in some form is enough to begin establishing the right of protection.

Disney said it was pleased with the ruling, and expects to win on appeal.