It is no surprise that the BBC, restricting itself to only one play for the Bard on the Box season, chooses Measure for Measure. Of all all the canon, it is surely the most relevant to the 1990s. Shakespeare never used the word “sleaze”, but his portrayal of the hypocrisy permeating Vienna uncannily mirrors the squalidness of our own troubled decade.

The play resounds with contemporary echoes: flawed justice, sexual obsession and duplicity, exposures of corruption behind the sanctimonious veneer of respectability, a threatening underclass. Issues of law and order find their modern counterparts as today’s battle-lines are drawn between those who see only that “liberty plucks justice by the nose”, and those who sceptically regard “proud man, dressed in a little brief authority”.

But Measure is not simply Shakespeare’s most modern play. It is positively post-modern in its uncertainties, ambiguities and silences. Small wonder it’s labelled a problem play. Its uncomfortable fascination is evident in how it has notoriously split critical judgment. Diametrically opposed evaluations ironically echo the title: measure for measure indeed.

The Duke has been seen as “essentially a wise and noble man” and as a “shifty cruel, offensive eavesdropper”. Attitudes to Isabella range from “fair and virtuous” to “a vicious sex hypocrite”.

Such openness to conflicting perceptions offers a host of opportunities to school and college students. The wealth of valid alternative interpretations makes Measure a key text in the realisation of a central aim of English and drama studies: the development of the informed imagination. Every student can be actively involved in ways far distant from the traditional reading round the class.

Crucial encounters throughout the play possess a vitality of language which generates its own motivating energies. In pairs or small groups students enact those meetings: the two sexually-charged confrontations of Angelo and Isabella; the fraught exchange between brother and sister, Claudio desperate for life, Isabella finally exploding in absolute rejection; the comic trial, funny in itself, but providing ironic commentary on the main plot’s themes of justice, sex and deceit; Lucio’s taunting of the disguised Duke.

Some speeches positively invite experiments in individual and group speaking: “Be absolute for death”; “Ay but to die . . .”; Isabella’s pleas against the tyranny of power. By active work, students find their own justified interpretations, not the handed-down opinions of convention. How does Angelo’s soliloquy of uneasy conscience, “When I would pray and think”, sound as a confession, a prayer, a public lecture, a voice from the psychiatrist’s couch?

The sexual politics of the play speak very directly to the preoccupations of older adolescents. The abstractions of justice and mercy spring to vivid life in the classroom as students discuss Angelo’s sexual blackmail and Isabella’s appalled response. “More than our brother is our charity” guarantees passionate argument. Should she have sex with Angelo to save her brother’s life? Interestingly, in 1994 the case for virginity gains more student support than it did two decades ago. Elsewhere, discussion of the choices facing characters invariably widens to invoke modern parallels. Today the detail of the Criminal Justice Act features strongly.

When students address how to stage the play, questions of politics, morality and sexuality fuse. Understanding emerges from very practical decisions. Just how do you portray a city in which a facade of justice barely conceals the corruption that boils and bubbles below? How does Isabella dress and behave? How might you stage all those dilemmas of the final act: the silence of Claudio and Juliet, the length of Isabella’s pause before she pleads for Angelo’s life; her reaction to the Duke’s proposal; the last stage-picture the audience will see before the lights fade? Such eternally open practicalities creatively engage students’ imagination, intelligence and feeling.

The RSC’s current production resolves such issues with endlessly inventive resourcefulness. Director Steven Pimlott’s portrayal of Vienna is less concerned with its seamy low-life than with the powerless position of women in a male world. In a brilliant coup-de-theatre 60 men appear on stage (yes, 60). Dressed in lawyers’ sober black, they virtually encircle Isabella and snigger at her words of shame. This savage indictment of male justice is tellingly underscored in a supremely cynical moment when the yobbish Lucio joins Angelo on the judges’ bench.

The production bristles with intelligent realisation of Shakespeare’s puzzles. Michael Feast’s deeply unsympathetic Duke makes a corkscrew seem arrowlike. Angelo is both metaphorically and literally buttoned up. Stella Gonet’s Isabella is an innocent, confident modern woman driven not by sexual hysteria, but by anger. Seeking to overcome male prejudice, she appears in the last scene dressed as a man.

It would be unfair to reveal how the silences and puzzles of Act 5 are staged. Suffice to say the production does full justice to the play’s enigmatic quality.

Measure for Measure is at the Royal Shakespeare Theatre, Stratford-upon-Avon. Tickets: 0789 295623. Running time 3 hrs 15 mins.