The New England Journal of Medicine, in an amicus brief filed today, expressed support for a Vermont law that forbids companies from mining drug prescription records for marketing purposes.

“We feel that the health professional-patient relationship should be confidential. [T]he data generated from such interactions should not be used for any purpose that does not have a direct salutary impact on the patient’s health,” Jennifer Zeis, a spokesperson for the New England Journal of Medicine, says.

The journal joins others, including the American Association of Physicians and Surgeons, who have sided with Vermont (represented by State Attorney General William Sorrell), in the case, Sorrell v. IMS Health.

Prescription records typically list the name of the doctor and the medications he or she prescribed. But these records also include other identifiers such as date of birth, gender and zip code which can be used to re-identify patients, according to the non-profit Electronic Privacy Information Center (EPIC) . This means that companies can easily search within patients records and obtain deeply private and sensitive information without their consent.

In the US only Maine, New Hampshire and Vermont have enacted laws barring data mining companies from using prescription drug records for commercial purposes. But in the past few years data mining companies challenged these laws, arguing that the restrictions are unconstitutional. An appellate court in Boston upheld prescription record data mining laws in Maine and New Hampshire but a US court of appeals in New York did not do the same for the Vermont law.

Data mining companies argue that putting limits on the use of drug prescriber information infringes on their rights of commercial free speech. But this sort of data mining infringes on doctor-patient confidentiality and patient privacy, says Kevin Outterson, one of the lawyers that filed today’s New England Journal of Medicine brief.

“The data that they are using,” says Outterson, “has been taken in violation of law without anyone’s consent and it’s just the same as if someone had stolen somebody’s property.”

The case is scheduled to be heard on 26 April 2011 by the US Supreme Court, which is expected to make its ruling June.