Delhi High Court Sends a Clear Message on Divisional Patents: Timing Is Everything

The Delhi High Court’s ruling in Yangtze Memory Technologie Co. Ltd. v. Union of India & Anr. delivers a sharp procedural reminder for patent applicants: the right to file a divisional application ends the moment the parent patent is granted.

The Court holds?

Interpreting Section 16(1) of the Patents Act, 1970, the Court reaffirmed that a divisional application may be filed only “at any time before the grant of the patent.” Once the patent is granted, the window closes - conclusively. The judgment clarifies the strict procedural boundaries governing divisional applications under Indian patent law and signals a heightened emphasis on applicant responsibility during prosecution.

Applicant’s Procedural Burden: The applicant sought to file a divisional application five days after the parent patent had already been granted, relying on an earlier conditional submission stating that it would be willing to file a divisional application if unity of invention objections were sustained. The statutory responsibility to seek division under Section 16(1) rests exclusively with the applicant. The right to file a divisional must be affirmatively exercised prior to grant; it cannot be presumed, inferred, or preserved through conditional statements.

No Corresponding Duty on the Controller: The Court rejected this position, firmly holding that the onus to file a divisional application rest squarely on the applicant. While the statutory scheme permits divisional filings either voluntarily or pursuant to a unity objection raised by the Controller, the Court clarified that the procedural framework does not impose any obligation on the Controller to keep the prosecution window open or defer grant merely because an applicant expresses a prospective or contingent intention to file a divisional application.

Binding Effect of Prosecution Conduct: Notably, the ruling also echoes the principle of prosecution history estoppel. The applicant had successfully argued that its claims constituted a single inventive concept in order to secure grant of the parent patent. Having obtained that benefit, the applicant’s subsequent attempt to file a divisional application was viewed as impermissible. The Court characterised this conduct as a “conscious election,” reiterating that parties cannot approbate and reprobate during patent prosecution.

Beyond its immediate facts, the judgment delivers a clear lesson; Divisional applications are not fallback safety nets. They must be filed proactively during prosecution-not reactively after grant. Conditional statements or post-grant reconsideration cannot revive statutory rights.

For patent applicants and IP strategists, this judgment underscores a simple but critical principle: divisional strategy must be timely, deliberate, and aligned with prosecution positions from the outset.

Yangtze Memory Technologie Co. Ltd. v Union of India & Anr. [W.P.(C)-IPD 10/2025], judgment dated February 3, 2026

Copy of the judgment can be accessed at: