Limits of Interrogatories in Patent Disputes
Facts of the Case
This case revolves around a patent infringement dispute in the pharmaceutical industry. The plaintiffs, Centrient Pharmaceuticals Netherlands B.V. and another entity, hold a patent numbered IN 247301. This patent covers a specific process for preparing Amoxicillin Trihydrate, which is a key ingredient used in antibiotics. The plaintiffs filed a commercial suit (CS(COMM) 218/2019) seeking a permanent injunction to stop the defendant, Dalas Biotech Limited, from using or infringing on this patented process. They claimed that the defendant was manufacturing Amoxicillin Trihydrate using a method that violated their patent rights.
To support their claim, the plaintiffs submitted test reports in their plaint (the initial court filing) to show that the defendant's product matched the one produced by their patented process. Under Indian patent law, specifically Section 104A(1)(b) of the Patents Act, 1970, once the patent holder proves possible infringement, the burden shifts to the alleged infringer (the defendant here) to prove they are not using the patented process.
The defendant filed a written statement denying the infringement. In paragraph 94 of this statement, they described their manufacturing process for Amoxicillin Trihydrate. However, the plaintiffs argued that this description was vague and full of ambiguities. For example, the defendant mentioned options like using "Penicillin G Acylase Enzyme" that could be either "immobilized or non-immobilized," or using acids like Nitric Acid, Sulphuric Acid, or Hydrochloric Acid interchangeably in the crystallization step. The plaintiffs claimed these "options" were added on purpose to hide the fact that the defendant was actually following the exact steps covered by the plaintiffs' patent.
Before filing this application, the plaintiffs sent a notice on August 2, 2019, asking the defendant to produce certain documents related to their manufacturing approvals and processes for inspection. The defendant responded partially on August 17 and 29, 2019, refusing to share most documents. They provided only their Drug Manufacturing License (No. Raj.2144) from the Drug Controller, Jaipur, Rajasthan, along with renewals, but withheld others like the Site Master File, Master Formula Records, and applications filed with regulatory authorities. The defendant said these were confidential and not required to be disclosed under the Drugs and Cosmetics Rules, 1945 (specifically Rule 76, which does not mandate revealing the exact process for getting a license).
The plaintiffs then filed this application (I.A. 15057/2019) under Order XI Rule 2 of the Code of Civil Procedure (CPC), 1908, as amended by the Commercial Courts Act, 2016, read with Section 151 CPC. This rule allows for discovery by interrogatories (written questions that the other party must answer under oath). The plaintiffs wanted the court to direct the defendant to answer specific interrogatories about their actual process and produce related documents. The prayer in the application was simple: allow the interrogatories and set a time limit for the defendant's response, plus any other relief the court deems fit.
The Dispute
The main dispute in this application was whether the court should force the defendant to answer the plaintiffs' interrogatories and disclose detailed information about their manufacturing process and regulatory filings. The plaintiffs argued that the defendant's written statement was evasive and not detailed enough to meet the burden under Section 104A(1)(b) of the Patents Act. They said the ambiguities (like optional steps) showed the defendant was hiding infringement, and without clear answers, the court couldn't properly decide if the patent was violated.
The defendant opposed, saying the interrogatories were irrelevant to the suit, sought confidential business information, and were just a "fishing expedition" to gather evidence instead of proving the case through trial. They argued that patent infringement suits focus on comparing the products (not digging into regulatory secrets), and such details should come out only during cross-examination of witnesses at trial, not through interrogatories.
In essence, this was a battle over discovery rights: How much detail must the defendant reveal early in the case to defend against infringement claims, especially when it involves trade secrets and regulatory approvals?
Detailed Reasoning
The court heard arguments from both sides. Let's break them down simply, keeping the legal points intact.
Plaintiffs' Arguments (Led by Mr. C.M. Lall, Senior Counsel):
- The suit patent (IN 247301) is for a specific enzymatic process to make Amoxicillin Trihydrate. The plaintiffs had already met their initial burden with test reports showing the defendant's product was identical.
- The defendant's paragraph 94 was "ambiguous and deceitful." It added "optionality" to key steps covered by the patent to pretend non-infringement. Examples:
- The enzyme (Penicillin G Acylase) is described as "immobilized or non-immobilized." But in real commercial production, it must be immobilized (fixed in place for reuse) because it's expensive (about 25 USD per kg, more than the selling price of the final product at 22 USD per kg). Washing the enzyme with water after use (as mentioned) proves it's immobilized, but the defendant hid this to avoid the patent claims.
- Using "/" for chemicals like salts of HPGM (likely PHPGME.HCl or PHPGME) suggests interchangeability, but they're not—the salt is more water-soluble and needs pH adjustments, while the free base has low solubility for better yield. This would require two different processes, making the description contradictory.
- In crystallization, the defendant lists three acids (Nitric/Sulphuric/Hydrochloric) as interchangeable "till clarity is achieved." But Sulphuric Acid forms an unacceptable salt at low pH (not safe for humans and can't achieve clarity), and Nitric Acid risks toxic byproducts (nitrosamines). Only Hydrochloric Acid works efficiently, which falls under the patent. Listing options hides the real use.
- For pH adjustment to crystallize the product, the defendant says add NaOH or NH3 until crystallization at pH 1.6 and 23-28°C. But in batch production (implied by seeding), pH must go up to 5 for minimum solubility (solubility drops from 48 mmol/kg at pH 1.6 to 4.7 mmol/kg at pH 5—a 10-fold decrease). Stopping at pH 1.6 would give a commercially unviable low yield.
- No regulatory body (like the Drug Controller under Drugs and Cosmetics Act, 1940) would approve a process with such vague options. The defendant must have filed a precise process to get their license (Raj.2144), so they should disclose it to prove non-infringement under Section 104A.
- The defendant's refusal to produce documents (Site Master File, Master Formula Records, etc.) shows bad faith. These would reveal the exact flow charts, steps, times, materials, and quantities—proving infringement.
- Interrogatories are needed for fair adjudication, as the written statement evades the burden of proof.
Defendant's Arguments (Led by Mr. Nalin Kohli):
- The suit is about patent infringement of IN 247301, not regulatory approvals or factory details. The court isn't the forum to question drug licenses—that's for the Drug Controller.
- The written statement clearly denies infringement and describes a non-violating process. The plaintiffs' claims of vagueness are based on guesses, not evidence.
- Interrogatories seek confidential info (facilities, chemicals, approvals) to spy on a business rival, not to resolve the suit. Under Indian law, there's no "patent linkage" (no mandatory check of patents during drug approvals).
- Burden of proof: Plaintiffs must first prove the defendant's product is identical to the patented one. Their test report is manipulated (challenged by defendant's third-party reports showing differences). Evidence like this needs expert witnesses and cross-examination at trial, not interrogatories.
- Citing Supreme Court in Raj Narain v. Smt. Indira Nehru Gandhi & Anr. (1972) 3 SCC 850: Interrogatories are narrower than cross-examination; relevant cross-questions aren't automatically interrogatories. They can't substitute for trial and can't be used for "roving inquiries" to build a case.
- The process in paragraph 94 is approvable under Rule 76 of Drugs and Cosmetics Rules, 1945—no need to disclose specifics for licensing. Plaintiffs are trying to fish for evidence instead of proving their own case.
Court's Analysis: The court focused on whether the interrogatories (listed in para 18 of the application) would help maintain the plaintiffs' case or destroy the defendant's, as per the general rule under Order XI Rule 1 CPC (interrogatories are allowed if answers advance the case).
- It noted the plaintiffs' main plea: The written statement is vague due to "optionality" in steps, so answers are needed (e.g., exact process filed with authorities, details in Site Master File/Master Formula Records like flow charts, step-by-step instructions, materials/quantities).
- But the court agreed with the defendant that the written statement sufficiently explains non-infringement—it's not vague. Regulatory approvals aren't the suit's subject; the focus is product identity under the patent.
- Burden under Section 104A(1)(b) Patents Act: Plaintiffs must prove infringement first (via product comparison). Their attempt here is to discover the defendant's "exclusive evidence" through fishing—e.g., demanding documents that reveal trade secrets.
- Interrogatories can't replace cross-examination. The "optionality" issues (enzyme, acids, pH) can be tested during trial by questioning the defendant's witnesses on credibility.
- Confidentiality: As business rivals, disclosing factory files (under Drugs and Cosmetics Act) isn't justified without clear relevance.
- Overall, the interrogatories go beyond scope—they're for trial evidence, not pre-trial discovery of opponent's secrets.
Decision
The court dismissed the application. It held that directing the defendant to answer the interrogatories would not serve justice, as it amounts to an impermissible roving inquiry. The issues can be resolved at trial through evidence and cross-examination. No merit in the application; it stands dismissed.
This decision emphasizes the limits of discovery in patent suits: Plaintiffs can't use interrogatories to force disclosure of confidential processes without strong proof of relevance, especially when trial mechanisms exist. It protects trade secrets while upholding the burden-shifting under the Patents Act.
Case Title: Centrient Pharmaceuticals Netherlands B.V. & Anr. vs Dalas Biotech Limited Order Date: January 27, 2021 Case Number: CS(COMM) 218/2019, CC(COMM) 19/2019, I.A. 15057/2019 (and other connected applications) Neutral Citation: AIRONLINE 2021 DEL 68 Name of Court: High Court of Delhi at New Delhi Name of Hon'ble Judge: Hon'ble Mr. Justice V. Kameswar Rao
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Written By: Advocate Ajay Amitabh Suman, IP Adjutor [Patent and Trademark Attorney], High Court of Delhi
