Next week, a play called Joe Guy opens at the Soho Theatre. It is billed as "a sensational story of identity, the corrupting power of celebrity, and the tensions between African and Caribbean communities" and is written by one of Britain's leading playwrights, Roy Williams. Who happens to be black. But what if he wasn't? Would we feel comfortable seeing a white writer take on such subjects?

British theatre has long boasted an admirable commitment to representing black and minority ethnic communities on stage. But over the past few years, a frustration has been building. On one hand libertarian commentators have begun to question this notion of playing "identity politics" with the arts, arguing that it is effectively racist to restrict writing plays about particular communities solely to members of that community. On another flank, there is increasing disquiet at the perception that black and minority ethnic writers are only being encouraged to write one sort of play - namely, naturalistic, issue-based, state-of-the-nation work.

It seems as if they are required to trade heavily on "authenticity" at the expense of more potentially speculative or metaphorical approaches. Non-white writers seem to be required by theatres to produce what, at times, amounts to emotional pornography - moreover, "authentic", "urban" or "exotic" emotional pornography. In their desire to commission new exciting work that is relevant to local communities, theatres often appear to apply an absurdly literal-minded approach to both representation and relevance.

Of course there is nothing wrong with a writer from a particular community wanting to write a play which is set within that community, and exploring the issues within it. Some spectacularly good plays have sprung from just such an approach. Roy Williams is an excellent example. His 2003 play Fallout remains, to my mind, one of the best plays written this decade. It is almost Shakespearean in its scope, and to simply describe it as a play about black-on-black gun crime is as stupidly reductive as describing Hamlet as a play about Dane-on-Dane violence.

At the other end of the spectrum are plays like Gurpreet Kaur Bhatti's Behzti, which achieved a spectacular level of national fame after it was effectively rioted off the stage and subsequently shut down. It is not, by any stretch of the imagination, a good play. Had it not been the cause of a riot, it would have sunk without trace, unseen and unremembered. The grim irony of the Behzti case is that Birmingham Rep, which commissioned the play, were seeking to put on a play that was "relevant" to the city's Sikh community by asking a Sikh writer to write a play about some Sikhs. Rarely has outreach work been so disastrously alienating.

The dual questions of authenticity and representation are difficult ones, but they need to be seriously addressed. Of course it is important for every community living in Britain to have an equal right to see itself portrayed on stage, and not just as an exercise in box-ticking and social cohesion. At the same time, it is crucial to remember that theatre's great strengths are not solely mimetic, realist or naturalistic, journalistic or documentary.

There is also a dire need for theatres to put more trust in writers' abilities - irrespective of colour or creed - to think beyond their own experiences and create astonishing works of imagination, while continuing to explore less narrow, literary models of play-making. On the other hand, would East is East have been taken at all seriously if it had been written by Sir David Hare? Do audiences really demand that their writers live in a near-approximation of the circumstances that they write about before they put pen to paper?