Claim Drafting and Specification Preparation
This domain tests the craft of drafting: how to structure a specification that satisfies s. 27(3), how to draft claims that are clear, supported and infringed, and how to avoid the sufficiency and overbreadth problems that invalidate patents. Questions often present a claim set and ask which claim is invalid or how to amend.
Specification requirements
- Section 27(3)(a): the specification must correctly describe the invention and its operation or use.
- Section 27(3)(b): claims must define the subject matter distinctly and in explicit terms.
- Section 27(4): a claim in respect of a machine may cover the use of the machine.
- Sufficiency: the description must enable the skilled person to make and use the invention without undue experimentation. The Consolboard test: the specification must be "a written description of the invention... sufficient to enable a person skilled in the art to put it into practice."
Claim structure
- Independent claims set the scope; dependent claims add limitations and provide fallback positions.
- Preamble should identify the category (art, process, machine, manufacture, composition) to anchor s. 2.
- Transitional phrases: "comprising" is open; "consisting of" is closed; "consisting essentially of" is partially open.
- Means-plus-function claiming is permitted but must be construed under s. 27(4) and the Free World Trust purposive approach.
- Omnibus claims ("as substantially described herein") are generally objectionable as not distinctly defining the invention.
Drafting for infringement
- Under Free World Trust v. Électro Santé (2000), claim elements are essential or non-essential; non-essential elements can be substituted without avoiding infringement. Draft claims with the minimum essential elements.
- Under Whirlpool v. Camco (2000), purposive construction considers the inventor's intention as expressed in the claims.
Worked example
An applicant drafts a single independent claim to a "system for processing data comprising means for receiving data, means for storing data, and means for outputting data." The examiner objects under s. 27(3)(b) that the claim is ambiguous. Analysis: means-plus-function language is permissible but must be linked to structure disclosed in the specification; if the specification discloses only generic hardware, the claim may be indefinite. The fix is to recite the structure (e.g., "a processor configured to...") and add dependent claims reciting specific algorithms.
Traps
- Using "comprising" in a claim intended to be closed.
- Drafting claims broader than the disclosure supports - s. 27(3)(b) and sufficiency attacks.
- Forgetting that the specification must describe the operation or use of the invention, not just its structure.
- Omitting a claim category that matches the commercial embodiment, leaving a gap for design-arounds.