Two Indian patents for sealing devices for electric meters, granted three years apart, both closely resembling a US patent that the Patent Office cited against neither. When the second patentee attacked the first, the courts had to work out which distinctions actually mattered.
The facts
Tara Chand Banka filed a patent application in 2001, granted in 2006 — after his death in 2005. The Patel Brothers filed a similar application in 2005, receiving their patent in 2008, along with design registrations.
In 2007, Banka’s son sued the Patel Brothers for infringement. They responded by petitioning the Intellectual Property Appellate Board (IPAB) to revoke Banka’s patent, contending it lacked novelty over US Patent 5782513 held by Nic Products Inc.
The IPAB’s decision
The IPAB found the patents substantially similar and revoked Banka’s patent, noting that the Patent Office had failed to identify the prior US art. It observed that the working of the invention was clearer and better defined in the US application.
The High Court’s reversal
The Calcutta High Court found the IPAB had overlooked critical distinctions:
- Banka’s transparent design enabled tamper detection — the practical point of a meter seal, and a function the opaque prior art could not perform; and
- his ribbed wire offered advantages the US patent lacked.
The court also noted that the expert testimony had not been cross-examined, and questioned the equity of the Patel Brothers challenging Banka’s patent when their own was similarly derived from the same source.
It directed the IPAB to reconsider within six months.
What the case exposes
Three things, each still worth attention.
Examination quality. The central embarrassment is that a US patent apparently anticipating both Indian patents was never cited during examination of either. The prior art was locatable; nobody located it. That failure produced two granted patents, an infringement suit, a revocation petition, an appeal and a remand — all of which a proper search would have avoided.
Distinctions that do work. The court’s approach is the useful part. Transparency was not decorative; it made tamper detection possible, which is the entire purpose of the device. A distinction that changes what the invention does is a real distinction, however small it looks alongside a diagram. An assessment of similarity that stops at appearance misses this.
Unchallenged evidence. Expert testimony that is not cross-examined cannot simply be adopted as though it had survived testing. The observation echoes the wider theme in Indian patent appeals — that tribunals must engage with the evidence rather than accept the more confident account.
And on the equity point: a challenger whose own patent derives from the same prior art is in an awkward position. It does not bar the challenge — a patent that lacks novelty should not survive because the person pointing it out has unclean hands — but the court was entitled to notice it.
A note on the forum. The IPAB was abolished in 2021 by the Tribunals Reforms Act. Patent revocation petitions and appeals from the Controller now lie before the High Courts, with the Delhi High Court operating a dedicated Intellectual Property Division. A dispute on these facts today would begin and end in the High Court.
The takeaways
- A missed prior art reference produced two overlapping patents — and years of litigation.
- Functional distinctions count — transparency enabled tamper detection.
- Uncross-examined expert evidence carries limited weight.
- The IPAB is gone — revocations and appeals now go to the High Courts.
Frequently asked questions
Why did the Calcutta High Court reverse the revocation? Because the IPAB had overlooked real distinctions — the transparent design enabling tamper detection and the ribbed wire — and relied on expert evidence that was never cross-examined.
Can a patent be revoked for lack of novelty over foreign prior art? Yes — prior art is assessed globally, and a foreign patent published before the priority date can anticipate an Indian patent.
Where are patent revocation petitions filed now? Before the High Courts. The IPAB was abolished in 2021 by the Tribunals Reforms Act.
Does it matter that the challenger’s own patent was similarly derived? It does not bar the challenge, but the court was entitled to weigh the equity of the position, as it did here.