Appeals court judges decided that the law was “a commercial speech restriction that does not directly advance the substantial state interests asserted by Vermont.”

The law would not have banned companies from collecting information on the prescribing habits of physicians, but would prevent them from selling it on to pharmaceutical manufacturers for the purposes of marketing new drugs to doctors – unless the doctor consents to having their information used in that way.

Vermont legislators claimed the new rules would prove effective in lowering healthcare costs by making it harder for drugs companies to sway physicians towards newer branded products over cheaper generic rivals.

But IMS, SDI and Source Healthcare Analytics – who jointly filed suit against the state – argued that “these types of laws do nothing to advance public health and in fact pose a risk to patients by arbitrarily delaying information on new medicine or warnings on existing medicines,” said IMS counsel Harvey Ashman.

More than 100 similar bills have been introduced in state legislatures across the country but only three have been passed into law, and none since 2007 when Vermont and Maine joined New Hampshire as the only three states to do so, the companies said.

On 13 December Vermont attorney general William Sorrell filed a petition with the Supreme Court for a writ of certiorari to review the appeals court decision.