Pharmaceutical companies are taking the government to court over a scheme which encourages doctors to switch patients to cheaper medications.
The Association of the British Pharmaceutical Industry (ABPI) has won a judicial review over the legality of offering doctors cash for moving patients on to lower-cost drugs.
It comes after the government launched a drive to get doctors to prescribe generic statins, rather than the more expensive brands.
Statins, which lower cholesterol, are taken by around two million people in Britain, and the Department of Health estimates that at least £84m a year could be saved by switching to cheaper versions.
The ABPI said it supports the NHS's desire to get the best value for money from all its suppliers.
But it claims there are "inadequate patient safeguards", adding there are two particular areas of concern.
The first is that "no central guidance was available to ensure that such switches were not being made without proper regard to the welfare of individual patients".
The second is that "additional payments to doctors were being made as a direct financial inducement to prescribe certain medicines in substitution for other named medicines, which the ABPI considers is illegal under European law".
A spokesman for the Department of Health said financial incentives "do have a place in the strategies employed by PCTs to get the best treatment for their patients".
But he said it is up to PCTs to decide the best use of their resources.