In May, the ministry of information and broadcasting banned some television commercials for men's deodorants claiming it wanted to curb ads "aimed at tickling the libidinous male instincts" and portraying women "as lustily hankering after men under the influence of such deodorants".

Throughout India there are restrictions on everything from women's attire to their conduct, all related in one way or another to preserving the oft-spouted gendered notion of "modesty." The "modest", "chaste", "decent" woman, if sexually assaulted, will get the sympathy and protection she deserves. The "forward", "outgoing" woman - often perceived as "tickling the libidinous male instincts" - will usually get little sympathy as a target of sexual assault, because she "invited" it.

This month's SlutWalk in Delhi is aimed at challenging negative stereotypes about women and girls who experience sexual violence and the police and judicial practices that reinforce these stereotypes. It's no surprise that the woman's "modesty" is frequently the focus instead of the inappropriate or violent conduct of men in complete disregard for women's dignity.

The application of "modesty" as a legal concept may have reached its nadir in a 1967 Supreme Court case. A man had been accused of sexually assaulting a seven-month-old infant, but India's antiquated, colonial-era criminal code does not define sexual assault or child sexual abuse. The law, however, prohibits "outrages" or "insults" against "modesty", leaving the court to determine whether the infant had "modesty" that could be "outraged".

So the Supreme Court, in finding the man guilty, created a test around whether a "reasonable man" would think his acts would outrage the modesty of a "reasonable woman" keeping in mind "all circumstances concerning her, such as, her station and way of life and the known notions of modesty of such a woman".

In 1995, instead of addressing sexual violence head-on, the Supreme Court took even greater pains to define "modesty", referring to English dictionaries: "Womanly propriety of behaviour; scrupulous chastity of thought, speech and conduct" and "decorous in manner and conduct; not forward or lewd".

Unfortunately, Parliament has done very little to address these legal absurdities, and the modesty test is routinely followed by all criminal courts today. In the 63 years since Independence, there have been various piecemeal amendments to the penal code and criminal procedures, but the government is yet to fill the definitional gaps around sexual assault and child sexual abuse.

The penal code defines rape as penetration, narrowly read as penile-vaginal penetration. All other forms of sexual assault, penetrative or not, are dealt with as outraging or insulting the "modesty" of women. Child sexual abuse remains clumsily and inadequately prosecuted under "unnatural offences", which criminalises a range of different acts, including oral sex and same-sex relations.

But these provisions on "outraging modesty" cause tremendous injustice to many women. For example, forcibly stripping and parading women naked, a practice that continues in many parts of India, is merely classified as outraging women's "modesty" despite the serious psychological and physical harm often inflicted. Last year, after a 15-year struggle for justice by a woman from the Bhil tribe who had been forcibly stripped, paraded naked and beaten, the Bombay high court handed out a one-year sentence.

Other grave forms of sexual assault, like sexual mutilation, are similarly categorised as outraging modesty or as causing grievous hurt or other offences. In the absence of a law governing child sexual abuse, many cases of sexual abuse of girls have been punished lightly as "outraging modesty".

The world over, including in India, activists have demanded that governments do away with the notion of "modesty" as a legal principle. Ideas of modesty and honour have formed the basis for violence, including so-called honour killings, in many parts of the world.

Instead, the laws governing sexual assault should be defined in terms of women's dignity and bodily integrity. The Supreme Court has in fact recognised that sexual assault is a violation of a woman's right to live with dignity, and it is time that this principle is embodied in India's laws.

What India urgently needs is a comprehensive definition of sexual assault recognising its different forms and the varying degrees of psychological and physical harm it causes. South Africa, for example, has a graded definition of sexual assault based on the gravity of the offence and resulting harm. The law criminalises both penetrative and non-penetrative sexual assault, sexual assault ordered by one person against another and "self-sexual assault", in which the offender forces the victim to perform sexual acts on herself.

Last year, the Indian government proposed much-needed reforms to the penal code to tackle sexual assault more effectively. Proposed amendments were circulated in March 2010 for comments from women's rights experts across the country. Rights groups in June 2010 reiterated their demand for a comprehensive definition of sexual assault that did away with the notion of "modesty" - but, more than a year later, the proposed reforms appear to be gathering dust.

Dangerously outdated notions of modesty should no longer be the basis for protecting Indian women and girls from sexual assault. The government should address the problem as it actually exists, not how it was perceived by 19th century British colonial administrators.