According to Fortune magazine, Julia Roberts is the most powerful celebrity in Hollywood. She is the only actress that can command a $20-million salary and for good reason. Her films routinely bring in more than $100 million dollars, the benchmark for economic success in the motion picture industry.

But Roberts is not infallible. People only want to see Roberts in a Julia-Roberts-type role.

For Roberts to maintain her popularity, she must take narrowly tailored roles that suit her strengths. She excels in roles that either showcase her likable, attractive, girl-next-door personality (Pretty Woman, My Best Friend’s Wedding, Notting Hill) or that make her a quick-thinking, intelligent problem solver (Conspiracy Theory, Thc Pelican Brief). When Roberts steps out of these prescribed niches, she is usually met with overwhelming failure (Michael Collins, Mary Reilly).

Luckily for the actress’s fans, director Stephen Soderburg does a fantastic job combining the two elements of the Roberts’ role in Erin Brockovich. Thanks to a push-up bra and cutoffs, the actress has never looked better as when she takes on a huge corporation that has been poisoning the drinking water of a small town.

Although the plot is somewhat laughable, the film is written in a tongue-in-cheek way that makes it seem like everybody knows how ridiculous it is. Besides Roberts’ performance, the latter attitude is the only thing that keeps the film from being decent rather than absolutely abysmal.

The film is about style – not substance; image, or content. In the last five years Soderburg has become a master of scene cuts, time bending, slow motion and cinematography. In recent years, he’s become one of the premier directors when it comes to style. Knowing these facts about the director, plus the aforementioned information about the star, the movie should not contain matters of serious weight. Yet it does.

For more than half the film, you basically see Brockovich underestimated because of her appearance. Whether it is job interviews or attempting to gain information for her lawyer bosses, Brockovich is constantly chided for the way she carries herself. This is entertaining, and more importantly, fits to the director’s and Roberts’ strengths. However, it just doesn’t jive with the second half of the film, where Brockovich attempts to litigiously fight the corporation that is causing cancer in children.

To her credit, Roberts is believable. Her motivations, efforts and actual results make sense pragmatically, but not in the context of the film. Erin Brockovich should be much lighter in tone or incredibly serious. The constant juxtaposition of serious material and humorous bits just doesn’t work.

You may question how the material could be manipulated, considering this is yet another picture supposedly based on a true story. Viewers most likely are wary of that clause by now, as they should be. When the goal of a movie is ultimately to make money, the exact telling of the truth is not always the highest priority. Fact is manipulated all the time in Hollywood.

Erin Brockovich is a watchable movie, and Roberts is as engaging as ever. However, the inconsistencies inherent in the construction of the film keep it from being better.

Erin Brockovich opens Friday.