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According to recent reviews of Steven Soderbergh’s new movie The Good German, Soderbergh uses the pseudonym Peter Andrews for his work as cinematographer on his films, and the name Mary Ann Bernard for his work as a film editor. Why do filmmakers use pseudonyms to conceal their involvement in a film?

Typically, pseudonyms are a product of the Byzantine rules that govern how credits appear in movies. As part of their contracts with the major studios, each of the various Hollywood labor groups (the Directors Guild of America, the Writers Guild of America, the International Cinematographers Guild, etc.) have strict rules that govern how their members are credited on screen.

But sometimes those rules conflict with filmmakers’ preferences. “My policy is to have my name on a movie only once,” Soderbergh says. “Having your name once increases the impact of that credit because I think every time you put your name up there, you’re actually diluting it.”

For his movie Traffic, he proposed that the credit read, “Directed and Photographed by Steven Soderbergh.” While the directors and cinematographers guilds both signed off on Soderbergh’s proposal, the Writers Guild would not, since its rules say no other credits can appear between the writer and director credit, and Soderbergh’s “directed and photographed by” solution would break that rule.

Soderbergh’s solution? The pseudonym Peter Andrews—his father’s first and middle names. A couple of years later, as his film Solaris wrapped up, Soderbergh encountered a similar issue with his film editor credit. Here, he opted for the pseudonym Mary Ann Bernard, based on his mother’s name. “I wanted to pay tribute to my dad, and so when the editing credit became an issue on Solaris, I decided to spread it around,” he says.

Soderbergh is hardly alone in his use of pseudonyms. When Joel and Ethan Coen edit their movies, they use the pseudonym Roderick Jaynes so as not to highlight their names too many times. Though the brothers work as a team, their standard credit sequence is for Joel to take director, Ethan to take producer, and for both to share the writing credit.

“Alan Smithee” is probably the most famous pseudonym, invented by the Directors Guild for directors who are so unsatisfied with a studio or producer’s meddling with their film that they don’t think it reflects their creative vision anymore. The first movie to use it was Death of a Gunfighter in 1969, and it has since been used dozens of times.

Pseudonyms are generally trouble-free, but they can create headaches around awards season. The Academy issues Oscar nominations to whoever is officially listed in a film’s credits, pseudonym or not. In 1997, Jaynes became an Oscar-nominated film editor for “his” work on Fargo. Likewise, Donald Kaufman, the fictional alter-ego of Charlie Kaufman who shared writing credit on 2002’s Adaptation, was nominated for best adapted screenplay.

The academy mostly leaves it up to Oscar nominees and winners to correct its records. This used to be an issue for writers who were blacklisted during the McCarthy era and couldn’t work under their own names. For instance, Dalton Trumbo won two Oscars under other names, once in 1954 for Roman Holiday as Ian McLellan Hunter, and then again in 1957 for The Brave One as Robert Rich. * While Trumbo had chosen to assume the identities of two different real people for those credits, and did not accept the awards himself, he eventually received both Oscars—for The Brave One in 1975, one year before he died, and for Roman Holiday in 1992. *

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Corrections, March 5, 2010: This article originally referred to Ian McLellan Hunter as Ian McCullen Hunter. It also stated that Robert Rich accepted an Oscar on Trumbo’s behalf in 1957. In fact, that award went unclaimed for a number of years. (Return to the corrected paragraph.)