ANY film containing the fluffy bundle of fun that is Reese Witherspoon is always going to be high on energy but it should also pack some substance as well.

This is why Legally Blonde (12) is something of a waste of talent, yet it so easily could have been a great film.

Witherspoon, who played an airhead in Clueless, Cruel Intentions and Freeway, is once again a scatty youngster with little else on her mind except hairdos, boys and fashion.

Her knowledge of the latter is so vast it has swept her to the top of her faculty at university, where she is studying for some fatuous degree that requires an in-depth knowledge of the history of polka dots.

But if she isn't smart she is certainly shrewd and it is on this premise the film looks as if it will make its mark, but it doesn't.

All blondes in films are portrayed as being thick as a concrete milkshake, but in this movie Witherspoon's character obviously knows more than she is letting on, happy to let her ditzy persona disarm people.

She is so good at this that her chinless fiancee dumps her just as he is about to start at Harvard Law School because he wants to be a senator before he is 30 and feels this is an unrealistic ambition with a dumb blonde on his arm.

Incensed by this, Witherspoon vows to succeed at Harvard as well and in the ludicrously contrived way that only Hollywood can achieve, she manages it.

Her high grades and a promotional video featuring her in a skimpy bikini are all that it takes to persuade the upper echelons at Harvard that what they really need to take the legal profession into the 21st century is a smiley Barbie doll with a pink fixation and a chihuahua called Bruiser. (The dog, by the way, gets way too much exposure. After American Sweethearts' insistence on doggy jokes last week, why is it Hollywood think dogs are riotously funny?).

So Witherspoon enrols at Harvard and the film meanders hopelessly while it retells the same joke over and over again, namely: Isn't it funny that a dizzy blonde with no hope of ever being a lawyer is wandering the same hallowed corridors as America's finest legal prospects?

Well yes, it is funny for a bit but the problem with the film is that at this point it runs out of things to say.

This is why it is such a wasted opportunity to make some real points about how people are judged and the value we place on appearance.

In an attempt to spin things out, Witherspoon finds herself assigned to the defence in a high profile murder case. It wouldn't need Mystic Meg to predict how this might turn out.

Equally predictably she finds a better partner than the shallow snob who dumped her, in the shape of homely egghead Luke Wilson.

Witherspoon is excellent in the role and makes the very most of the thin material provided.

In many ways it is no different to the part she had in Clueless, but that had Jane Austen as its source material while this is mainly an Erin Brockevich for the under nines.

Gary Lawrence