Regardless of the logic or the lack of logic behind the ‘6 year rule’, the fact remains that several judgments, especially Delhi High Court judgments picked up on this rule and applied it in several cases to deny interim injunctions in all those cases of patent infringement where the patent was less than 6 years. Although this 6 years rule has never formed the only basis in law to deny an injunction it was mentioned quite regularly without even pausing to understand or mention the reasons for fixing 6 years as a benchmark.
The possible logic behind the rule: Traditionally even English Courts were reluctant to grant interim injunctions when the patent was relatively new because of the fact that the process to grant a patent was quite complex and more often than not it could be presumed that a patent office would err in the grant of a patent. However this was the situation in England before it introduced post-grant opposition mechanisms. With the introduction of the post-grant opposition mechanism the quality of patents was presumed to have increased since there was now an opportunity to challenge a patent soon as it had been granted. In American Cyanamid Lord Diplock pointed out how the post-grant opposition mechanism had attached to all patents a stronger presumption of validity.
The Delhi High Court adopting the rule: The Delhi High Court however not only borrowed on this rule from Manicka Thevar but also proceeded to hold in the case of N.R.D.C, New Delhi v. The Delhi Cloth and General Mills Co. Ltd. and Ors (1980) that as “a rule of practice that if a patent is a new one, a mere challenge at the Bar would be quite sufficient for a refusal of a temporary injunction”. Amongst other cases this proposition was followed unquestioningly by the Delhi High Court in the Standipick case (2000) and once again in the relatively recent Bilcare (2007) case. It was only in theRoche v. Cipla case (2008) that Justice Bhat of the Delhi High Court finally paused to question the logic of this rule and also express his “bafflement” at this rule. In relevant part he laid down that the 6 year rule “has to be seen as a rule of caution and prudence rather than a rigid, ritualistic formula of mathematical application.”