I agree that taxing sanitary pads is discriminatory toward women. However, I would invoke Article 14, Article 15(1) and Article 21 to argue this point.
Also, Gautam Bhatia's very well-intended discussion of this while very appreciable, labors a bit too much in my opinion, on countering objections that to my mind are objections which are not very convincing to begin with.
I would put the case like this. Sanitary pads are essential items for menstruating girls and women and the majority of Indian girls and women need to use them for at least 40-45 years of their lives. These are not luxury items but are indispensable for a menstruating female to live with dignity and to participate in human activity and in family and social life. A housewife needs these as much as a schoolgirl as much as a woman who goes out to work and as much as a woman farmer, etc.
In the 21st century, the right to access and use sanitary pads could well be considered a human right of all women.
Sanitary pads are also an essential item for reproductive health and overall health and again this will invoke the Article 21 right to life argument.
Now why does the State exempt goods from tax. If one looks at the list at http://allindiantaxes.com/pdf/23123da1.pdf and probably if one checks the relevant notifications etc., one of the reasons is to exempt those goods that are indispensable for the poor to survive. The State acts as a welfare State here and refuses to tax those goods that are essential for the poor to survive.
Also certain essential items related to human activity are exempt.
Thus agricultural implements, handicapped aids, bread, charcoal, condoms and contraceptives, electricity, human blood, indigenous soap, newspaper, meat, grains, rakhi, salt, semen, sugar, seeds, textiles, tobacco, toddy, water, clay idols etc., are all exempt from tax.
The intent behind notifying an item as tax free in such cases appears to be an intent to not burden the consumer with tax because of the nature of the item and its perceived indispensability/ significance to the user or because the State does not want to discourage its use by taxing the item. In these cases, the rationale is to keep the item cheaper for the consumer.
In some other cases, the rationale is to not burden the manufacturer.
Now I would argue that sanitary pads are essential for a woman's right to live with dignity and with freedom and also for her overall health, not just reproductive health. A sanitary pad is as essential as condoms and contraceptives. In fact a sanitary pad is more essential as there is no element of choice in the needs for sanitary pads. A man may or may not choose to have sex, but a menstruating woman has no control over her periods.
I would argue that by failing to apply the same criteria to sanitary pads as to these other items listed above, the State is failing in its duty to treat women with equality and is discriminating against women.
I would place data and facts before the Court, pointing out how the usage of sanitary pads in India is still very low as compared to other more developed countries. I would show how lack of access to sanitary pads is responsible for the deterioration in the quality of life for girls and women. How it adversely affects their dignity, their freedom, their physical and mental health, their confidence, their self-esteem, their participation in education and in the work force, their ability to travel and move freely, their ability to participate in physical activity, etc. I would use data to show that the high cost of sanitary pads is a factor for their low usage in India.
I would in fact argue that the State needs to go further and subsidize sanitary pads in India. These should also be distributed free in schools and to other needy women.