In February HBO released “Allen v. Farrow,” a four-part docuseries that examined the events that led up to Dylan Farrow’s sexual abuse allegations against her father, Woody Allen. That same month Skyhorse Publishing threatened a copyright infringement lawsuit against the premium cabler and the docuseries’ directors, Kirby Dick and Amy Ziering, over the series’ use of unauthorized audio excerpts from Allen’s 2020 memoir, “Apropos of Nothing.”

In the four months since Skyhorse publicly contemplated a lawsuit, one has yet to appear, ostensibly due to a legal doctrine called Fair Use. While it’s not a fixed exception with clearly defined borders, the Fair Use doctrine has successfully transformed the documentary landscape in the past two decades.

“Film is a visual medium and if key material, say a film clip, is exorbitantly priced and takes up an outsized fraction of your budget and [therefore can’t be used], the film suffers,” says director Matt Tyrnauer. “If Fair Use didn’t exist, the visual language of documentaries as we now know through them would suffer. So, the Fair Use doctrine not only saves the genre, but also elevates it.”

Fair Use makes it clear that copyright cannot become a form of private censorship by promoting freedom of expression and permitting the unlicensed — i.e., the unauthorized, free use — of copyright-protected works in certain circumstances. Filmmakers, news gatherers, critics or educators can use copyrighted works (audiobooks, movies, music, photographs, etc.) without permission if the asset adds context to a project.

The most complicated part of Fair Use is determining how much unlicensed content can be used. Creators can only invoke what is “reasonably appropriate” of the copyrighted material, in terms of length, to illustrate or sufficiently support the point being made. There are no stated time minimums or maximums. Filmmakers alongside their lawyers must determine how much screen time they will give unlicensed materials.

“There is nothing protected by copyright law which is not also subject to Fair Use,” says entertainment lawyer Michael Donaldson. “Because in the copyright law, it says very explicitly that Fair Use is not an infringement of copyright. It’s an exception.”

In Tyrnauer’s most recent doc project, Showtime’s four-part “The Reagans” about Ronald and Nancy Reagan’s path from Hollywood to the White House, he relied on archival footage and talking heads to tell their story. While 15% to 20% of the series’ budget went toward licensing copyright-protected materials, the Fair Use doctrine allowed the director to include various segments of old movies starring Ronald Reagan.

“If you want to show the work of your main character in his career as a movie star, it is absolutely essential to incorporate” those film clips, Tyrnauer says. “If you’re not able to do that, you are not able to tell the story. And if you’re not able to pay the exorbitant fees that the licensor is asking for, then you’re out of luck.”

That is unless you are Ken Burns. Responsible for directing the highly lauded PBS documentaries including this year’s “Hemingway,” Burns and his team “license the archival material they determine requires permission,” says the director’s longtime publicist Joe DePlasco.

Burns co-directed “Hemingway,” about the iconic American author Ernest Hemingway, alongside Lynn Novack. The six-hour series features rarely seen photographs, archival footage and Hemingway’s original manuscripts. While it isn’t clear if public domain played a role in Burns’ accessing the author’s materials, it’s apparent that the project required a hefty budget not afforded to most documentarians.

Licensing the rights to copyrighted materials has been in practice in the documentary genre for decades. But securing the rights to such materials proved difficult, prohibitively expensive to most productions and risky if the legal rights holders felt that their copyright had been infringed upon in any way.

Despite being a century old doctrine, Fair Use became more feasible to filmmakers in 2006 thanks to Donaldson’s work on Kirby Dick’s “This Film Is Not Yet Rated.” Known in the doc community as the Fair Use guru, Donaldson worked with Dick to justify his incorporation of 134 movie clips into “Not Yet Rated” under Fair Use. The clips were employed to illustrate and support the inconsistencies within the MPAA ratings system. No movie studios threatened to sue or ever sued Dick.

While “Not Yet Rated” and an American University booklet entitled “Documentary Filmmaker’s Statement of Best Practices in Fair Use” set things in motion for Fair Use to be utilized more often in nonfiction films, the playing field still wasn’t level.

“At that time, you could not get insurance for material used pursuant to Fair Use,” says Donaldson. “So, I started negotiating with insurance companies. After a year I finally got one company to agree [to insure Fair Use].”

The company was Media/Professional Insurance. In 2007 it began providing filmmakers with Error and Omissions (E&O) insurance against claims arising out of Fair Use of copyrighted material. With E&O insurance in place, copyright holders lost the upper hand and filmmakers were able to stand up for their Fair Use rights.

“Going Clear: Scientology and the Prison of Belief,” 20 Feet From Stardom” and “I am Not Your Negro” are among the countless documentaries that could not have been made or were elevated by Fair Using footage.

IMDb TV’s five-part docuseries “Moment of Truth” is yet another nonfiction title that relied on Fair Use. Directed by Clay Johnson and Matthew Perniciaro, the series examines the 1993 murder of Michael Jordan’s father, James. Like Tyrnauer, the co-directors both licensed and Fair Used footage including basketball material pertaining to Michael Jordan and specific national news segments.

“Right now, in our society, documentaries have the ability to reach audiences more than they ever have before in history,” Perniciaro says. “Fair Use allows filmmakers like me to tell the best version of the story and create that full 360-degree experience for a viewer.”