Jurassic Park changes the lawyer, Donald Gennaro, from the book; here's why director Steven Spielberg's characterization doesn't make sense.
When Steven Spielberg adapted Michael Crichton's novel Jurassic Park, he fundamentally changed the lawyer character, Donald Gennaro — but the new characterization doesn't make sense. Both versions of the story center on an ill-fated theme park based around living dinosaurs that were brought to life via advanced cloning technology. Although Jurassic Park changes several aspects of the book, both versions share the same basic characters and plot points.
In Crichton's novel and the feature film, the characters are brought together on Isla Nublar to assess the amusement park's safety. The top-secret "biological reserve" is home to various dinosaurs, who were created by combining recovered (damaged) DNA from fossils and supplementing it with compatible DNA from living amphibious, reptilian, and avian creatures (the biological descendants of dinosaurs). The entrepreneur and visionary John Hammond in Jurassic Park "spared no expense" in creating his park — which, coupled with the mysterious "animal attacks" on construction workers, has investors worried.
Donald Gennaro is the lawyer acting on behalf of investors in both versions of Jurassic Park. He visits Isla Nublar with chaos theorist Ian Malcolm to determine if the venture is safe. Apart from the background, however, the two versions of the character are starkly different: not only is his personality and motivation changed in the movie adaptation, but his role in the overall story is significantly minimized. As a result of these changes, Donald's character in Spielberg's Jurassic Park is undermined — to the point of verging on being a plot hole.
In Jurassic Park, Gennaro is a lawyer working on behalf of a client who has invested in John Hammond's venture. An important point of distinction is that Genarro himself is not an investor. Donald Gennaro is changed to a villain in Jurassic Park the movie, rather than one of the heroes — but the motivation makes no sense. In the Crichton novel, Gennaro is an "everyman" character through which the reader can experience the action. Once he recognizes the danger the park poses, he quickly abandons his concerns about his job and instead takes an active role in trying to stop the disaster from unfurling. He fights off Velociraptors and is one of the survivors who escape at the end of the book.
In Spielberg's movie, however, Gennaro is a two-dimensional, unsympathetic creep who is consumed by greed. He is blinded by the financial potential of Jurassic Park, excitedly speculating about the fortune that could be made, and showing no concern for the ethics of the park or the potential danger. Gennaro is also a coward: he abandons the two kids, Lex and Tim Murphy, at the first sign of danger — and as a result, gets arguably the franchise's most humiliating death when a Tyrannosaurus rex eats him off of a toilet. The moment is frightening and builds suspense, but is also framed as comedic, which drives home just how unlikable this version of the character is intended to be.
Since Gennaro is not actually an investor, however, his brief arc in Jurassic Park is a bit of a plot hole. The movie never explains how he stands to gain from the park's profits. Sure, he may have some sort of stock option from InGen as a part of his employment (he's the general counsel), but that doesn't explain why he went from threatening to shut the park down to excitedly raving about how much money could be made. Most likely, Gennaro took on these characteristics to balance out the fact that Jurassic Park changes John Hammond to be much more likable — or perhaps Steven Spielberg just really dislikes lawyers.
