Carmen lives with her husband and two children in Mozambique. She is HIV positive, but she lives a happy and healthy life thanks to affordable medicines she receives through a government programme supported by Mêdecins Sans Frontires (MSF).

But this month, Carmen's future, and the future of millions of other patients across the developing world is being played out in the Indian courts. Two multinational drug companies - Swiss Novartis and German Bayer - are each headed to the courts in separate attacks on what India has done to increase access to more affordable medicines, specifically those to treat cancer.

Why should Carmen be so interested in the outcome of legal battles happening on the other side of the world, over drugs to treat a disease she doesn't even have? Although she may not know it, she has a vested interest in these cases. If a verdict is handed down in favour of the drug companies, it could slowly choke the lifeline of affordable medicines that India produces - and on which Carmen, and millions of others like her, rely.

The Novartis dispute goes back to 2006, when the company was denied a patent in India on imatinib mesylate, a leukaemia drug which Novartis markets under the brand name Glivec.

India's patent law makes it harder to get a patent on new forms of existing medicines, unless they show significantly improved 'therapeutic efficacy'. Just putting three pills in one or using known industry practices to formulate a drug are not considered innovative enough in India to warrant a new 20-year patent.

The spirit of the Indian law is to not just incentivise research and development on new drugs, but also to stop drug giants from indulging in 'evergreening, ' a common practice in the pharmaceutical industry. A single medicine can have several applications for separate patents, each relating to a different aspect of the same medicine.

This is a lucrative game, but a deadly one too. The high prices of medicines that stem from monopolies can mean the difference between life and death.

Competition among multiple generic manufacturers - which can thrive when patent monopolies don't stand in the way - is what brings drug prices down. In 2001, it was competition from Indian manufacturers that drove the price of antiretroviral (ARV) drugs to treat HIV down from over Rs 4. 7 lakh per patient per year to around Rs 8, 300 today.

This saves lives. It's what made it possible for HIV treatment to be scaled up through treatment providers like MSF. Today, eight million people receive treatment, enabling them to live active and productive lives;Carmen is one of them.

For the past six years, Novartis have sought to use litigation to remove the tougher standards for patentability from India's patent law. Novartis is now before the Supreme Court, and is trying a new tack. Having failed to have the law declared unconstitutional, it now wants to gut it of any substance. The company is seeking to have the law interpreted in a way that its public health benefits become meaningless.

The legal exclusion of patent barriers on medicines enabled India to produce quality, affordable, generic versions of medicines, and earned India the nickname 'pharmacy of the developing world'. Over 80 per cent of the ARVs MSF uses to treat more than 2, 20, 000 people in 23 countries are produced in India. Novartis is putting this at risk. If it wins, India will grant far more patents on medicines. As a result, a single medicine can be protected by a large number of separate patents and this will limit the supply of affordable generic medicines.

And what of Bayer? While the legal battle between Novartis and India over what deserves a patent reaches its climax, Bayer is trying to straightjacket India's attempts to ensure people have access to the medicines that have actually been patented and are very expensive. India does grant patents (although the drug company hype often brushes over this fact). Currently, and notwithstanding Novartis, it does so only for those medicines that are offer greater medical benefits.

In fact many of the newest HIV drugs are already patented in India. This already poses a problem of access, as the production of affordable generics is blocked. For example, one of the HIV drugs we use in our Mumbai clinic, raltegravir, costs MSF almost Rs 1 lakh per person per year, for just one of the drugs in a threedrug cocktail. This is because there is just one producer that can charge any price they choose. From a public health point of view, scaling up treatment to large numbers of people, and keeping them on treatment long term, won't be possible with prices like these.

Action will have to be taken if access is blocked by high prices or lack of supply. One solution is a legal mechanism in patent laws around the world - a 'compulsory licence' - which authorises price-lowering generic production, in return for royalty payments to the patent owner. In a landmark decision in March, the first Indian compulsory licence was issued, so that a generic company can produce sorafenib tosylate, a liver and kidney cancer drug patented by Bayer.

This mechanism was used because Bayer had failed to make the drug available and affordable at a reasonable price. Bayer's drug, marketed as Nexavar, costs over Rs 2. 8 lakh for one month's treatment. The new generic version would cost Rs 8, 800 per month;a price reduction of 97 per cent.

This decision established a precedent, and shows generic production is still possible in India, not just for cancer patients but also for people living with HIV and other diseases, to ensure low-cost generic competition. Bayer, predictably, chose to appeal. The appeal was heard earlier this month - we are now waiting for a judgment.

Much hangs on the outcome of both cases. A Novartis win could lower the bar for innovation in India, allowing for more widespread patenting in the short run, making it easier for companies like Novartis to get patents on drugs already in the public domain;and in the future enabling companies to defer the date their products go off-patent in India. A Bayer win would close the door on a potential watershed for affordable generic versions of patented medicines.

Either way, it would mean higher drug prices for people in India and across the developing world. Behind the legal jargon, lives are at stake.