Linfo IP LLC v. Ziprecruiter Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Linfo IP, LLC (Texas)
  • Defendant: Ziprecruiter, Inc. (Delaware)
  • Plaintiff’s Counsel: Andrew M. Ling P.C.
• Case Identification: 2:25-cv-03718, D. Ariz., 10/07/2025
• Venue Allegations: Plaintiff alleges venue is proper in the District of Arizona because Defendant has committed acts of infringement and maintains a "regular and established place of business" in Phoenix, Arizona.
• Core Dispute: Plaintiff alleges that Defendant’s online job search platform infringes a patent related to automated methods for analyzing unstructured documents, like resumes and job descriptions, to generate relevant search queries.
• Technical Context: The technology at issue addresses automated systems for matching job seekers with job postings by programmatically analyzing the text of a source document to identify and weight key terms, thereby creating a search query without manual user input.
• Key Procedural History: The complaint notes that Plaintiff and its predecessors have entered into settlement licenses with other entities, but alleges these licenses did not grant rights to produce a patented article and therefore do not trigger patent marking requirements.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,665,641 - System, Methods, And User Interface For Automated Job Search

The Invention Explained

• Problem Addressed: The patent's background section describes the difficulty of searching unstructured text documents like resumes and job postings. It states that conventional keyword-based searches are often ineffective because a few keywords cannot adequately represent the complex requirements in a job description. Furthermore, it notes that manually reading a document to distill its key requirements into an effective search query is a time-consuming and skill-intensive process (’641 Patent, col. 1:31-40).
• The Patented Solution: The invention proposes a method to automate this process. It "automatically analyze[s] the content of a resume document or a job description document and transform[s] the document into a search query" without requiring the user to read the document (’641 Patent, col. 1:58-62). The system identifies key terms (e.g., skills, job titles) and assigns them an "importance score" based on contextual and semantic analysis of the surrounding text. For example, terms associated with phrases like "must have" receive a higher weighting co-efficient than terms associated with "plus" or "nice to have" (’641 Patent, col. 4:26-39). This scored set of terms is then used to automatically construct and execute a search against a database of corresponding documents.
• Technical Importance: This approach was designed to improve the relevance of search results in the recruitment field by moving beyond simple keyword matching to a more nuanced, automated analysis of a document's full text (’641 Patent, col. 2:3-6).

Key Claims at a Glance

• The complaint asserts infringement of one or more of claims 1-20 (Compl. ¶9). Independent claims 1 and 8 are asserted.
• Independent Claim 1 (Method): The essential elements include:
  • Receiving a resume document.
  • Using the resume document as a query to search job description documents.
  • Performing a search and determining a relevance score.
  • The relevance score is produced by a multi-step process: (1) analyzing the resume, (2) identifying a group of terms representing elements like a skill or job role, (3) assigning a "term importance measure" based on a machine-performed analysis, (4) matching that term to terms in a job description, and (5) producing the final score based on the importance measure.
• The complaint reserves the right to assert dependent claims (Compl. ¶9).

III. The Accused Instrumentality

Product Identification

The accused instrumentality is Defendant's "system with methods and user interface for discovering information in a text content and extracting and presenting the information," as embodied in its online job search platform (Compl. ¶9).

Functionality and Market Context

The complaint alleges that Defendant "maintains, operates, and administers" a system for automated job searches (Compl. ¶9). A URL provided in the complaint points to a job search results page on the ziprecruiter.com website, suggesting the accused functionality involves the backend processing that powers the search and the frontend user interface that presents the results (Compl. ¶12). The complaint does not provide specific details about the technical operation of the accused system.

IV. Analysis of Infringement Allegations

The complaint references a "preliminary exemplary table attached as Exhibit B" to provide support for its infringement allegations but does not include the exhibit (Compl. ¶10). The narrative theory is that Ziprecruiter's system performs an infringing method for discovering, extracting, and presenting information from text content such as job postings (Compl. ¶9). Without the referenced claim chart, a detailed element-by-element analysis based on the complaint is not possible.

No probative visual evidence provided in complaint.

• Identified Points of Contention:
  • Scope Questions: The complaint alleges infringement by a "system with methods and user interface" (Compl. ¶9). A potential point of contention may be whether Ziprecruiter's system, as a whole, performs every step of the claimed method. For example, Claim 1 recites "receiving a resume document" and "using the resume document as a query," which raises the question of whether this applies to user-entered keyword searches or only to functionality that directly ingests a full resume document to initiate a search (’641 Patent, cl. 1).
  • Technical Questions: A central technical question will be whether Ziprecruiter's search algorithm performs the specific step of "assigning a term importance measure... based on a machine-performed analysis" as required by Claim 1 of the ’641 Patent. The complaint does not provide any evidence detailing how the accused system technically operates or calculates relevance, which will be a key subject for discovery.

V. Key Claim Terms for Construction

• The Term: "term importance measure"

• Context and Importance: This term is central to the claimed invention, as it defines the core mechanism for scoring and ranking terms to create an automated query. Its construction will be critical to determining both infringement and validity, as it distinguishes the invention from generic keyword searching.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The claim language describes the measure as being based on a "machine-performed analysis of the first term," which could be argued to encompass any algorithmic scoring of a term's relevance within a document (’641 Patent, cl. 1).
  • Evidence for a Narrower Interpretation: The specification provides specific examples of how this measure is calculated, such as by assigning a "weighting co-efficient" to a skill name based on its proximity to an "importance specification term" (e.g., "must have" = 1.0, "preferred" = 0.6) (’641 Patent, col. 4:26-39). A defendant may argue that the term should be limited to this specific semantic weighting methodology.

• The Term: "analyzing the resume document"

• Context and Importance: This is the foundational step in the patented process for generating a relevance score. The scope of "analyzing" will dictate what types of automated processing fall within the claim.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: This phrase could be interpreted broadly to mean any form of automated parsing or data extraction from the document's text.
  • Evidence for a Narrower Interpretation: The patent's abstract and summary describe the analysis as identifying the "most representative attributes" based on "grammatical, semantic, and contextual information" (’641 Patent, Abstract; col. 1:65-67). This may support a narrower construction requiring a more sophisticated linguistic analysis than simple keyword identification.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement, stating Defendant encourages its customers to use its products and services in an infringing manner (Compl. ¶11). It also pleads contributory infringement, alleging the accused services are not a staple commercial product and that their only reasonable use is an infringing one (Compl. ¶12).
• Willful Infringement: The willfulness allegation is based on knowledge of the patent "from at least the filing date of the lawsuit," a standard pleading for post-suit willfulness. The complaint reserves the right to amend if pre-suit knowledge is discovered (Compl. ¶11, fn. 1).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of definitional scope: can the claim term "term importance measure" be construed broadly to cover modern, generalized relevance-scoring algorithms, or is it confined to the specific semantic weighting system detailed in the patent's specification, which relies on identifying and scoring explicit modifiers like "must have" or "preferred"?
• A key evidentiary question will be one of technical proof: given the absence of specific technical allegations in the complaint, what evidence can the plaintiff discover and present to show that the internal workings of Ziprecruiter's proprietary search system perform the specific, multi-step analytical process required by the asserted claims?