Microsoft Corp v. Enfish LLC

1. Case Identification

• Case #: IPR2014-00577
• Patent #: 6,163,775
• Filed: April 3, 2014
• Petitioner(s): Microsoft Corporation
• Patent Owner(s): Enfish, LLC
• Challenged Claims: 16-18, 24-29, 46-48, and 54-59

2. Patent Overview

• Title: Self-Referential Database System
• Brief Description: The ’775 patent describes a database system featuring a flexible, self-referential logical table that stores both data and schema information. The invention centers on three main concepts: a single logical table structure, the use of variable-length object identification numbers (OIDs) to identify rows and columns, and a bi-directional indexing method for contextual searching.

3. Grounds for Unpatentability

Ground 1: Anticipation over Smith - Claims 17, 24-26, 47, and 54-56 are anticipated by Smith under 35 U.S.C. §102.

• Prior Art Relied Upon: Smith (Patent 5,404,510).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Smith, which is directed to designing and optimizing indexes in a relational database management system, discloses every element of the challenged claims. Smith teaches a database system with logical tables comprising rows and columns (records and attribute sets), where each is identified by an OID (e.g., "employee ID" for records, "column object id" for attributes). Petitioner asserted this structure meets the base limitations of the independent claims. Smith further explicitly teaches the additional limitations of claims 17 and 47 by disclosing a "means for indexing data stored in said table." For claims 24 and 54, Smith's disclosure of using an "Index Id" as a foreign key in other tables meets the limitation of a cell including a "pointer to an index record."
  • Key Aspects: This ground was presented as a direct response to the Patent Owner’s narrowed construction of "OID" in parallel litigation, as Smith allegedly discloses the specific "immutable" or "persistent" object IDs that the Patent Owner argued were required by the claims.

Ground 2: Obviousness over SQL-92, Gardarin, and Smith - Claims 16 and 46 are obvious over SQL-92 in view of Gardarin and Smith under 35 U.S.C. §103.

• Prior Art Relied Upon: SQL-92 (an ANSI Standard), Gardarin (a 1992 publication on extending SQL), and Smith (’510 patent).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that SQL-92, a dominant database standard, provides the foundational database structure with tables, rows, and columns. However, the Board previously determined SQL-92 alone did not sufficiently disclose using a variable-length data type as a primary key. Gardarin was introduced to cure this deficiency, as it explicitly teaches the combination of variable-length types and primary keys in an SQL context. This combination allegedly meets the key limitation of claims 16 and 46: "wherein said OIDs are variable in length." Smith was added to provide the teachings for an efficient indexing system.
  • Motivation to Combine: A POSITA would combine the industry standard SQL-92 with Gardarin because Gardarin is an explicit improvement on an interim version of that same standard, teaching a desirable feature. A POSITA would further incorporate Smith's teachings because the SQL-92 standard intentionally omitted a standardized indexing approach, encouraging developers to implement their own optimized solutions like the one described in Smith.
  • Expectation of Success: Combining a database standard with a known extension and a well-understood indexing optimization technique would have yielded predictable improvements in database functionality.

Ground 3: Obviousness over Smith, Clifton, and Salton - Claims 28-29 and 58-59 are obvious over Smith in view of Clifton and in further view of Salton under §103.

• Prior Art Relied Upon: Smith (’510 patent), Clifton (a 1990 publication on hypertext indexing), and Salton (a textbook on information retrieval).

• Core Argument for this Ground:

  • Prior Art Mapping: This combination builds upon Smith as the base relational database system. Clifton was introduced to teach secondary indexing, where a retrieved result points to a secondary index, which Petitioner argued meets the limitations of base claims 27 and 57 related to locating an index record pointed to by a retrieved cell. Salton, a foundational textbook on information retrieval, was then added to teach the advanced search features required by dependent claims 28-29 and 58-59, namely the "weighing means for weighing key words" and the filtering of common "stop words" to improve search relevance.
  • Motivation to Combine: A POSITA seeking to enhance the search capabilities of the Smith database would have been motivated to look to analogous art. They would consult Clifton for more advanced indexing structures and turn to a canonical text like Salton for well-known methods of improving search result relevance, such as term weighting and filtering.
  • Expectation of Success: Applying established information retrieval techniques from a standard textbook like Salton to a database system like Smith's was a common and predictable method for improving search performance.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 18 and 48 are obvious over Smith in view of VB3 (Visual Basic 3.0 manuals), and that claims 27 and 57 are obvious over Smith in view of Clifton.

4. Key Claim Construction Positions

• "object identification number (OID)": This term was central to the petition. Petitioner noted the Board had previously construed it as "an array of bits that define an object." However, Petitioner's primary justification for this second petition was the Patent Owner's recent advocacy in district court litigation for a much narrower construction, where OIDs must be "immutable and completely independent of changes in data value or physical location." Petitioner argued that its new grounds, particularly those relying on Smith, squarely address this narrower construction.
• "means for configuring memory...": For this and other means-plus-function terms, Petitioner argued that the ’775 patent fails to disclose a specific algorithm. Therefore, under the broadest reasonable interpretation, the corresponding structure is simply a "general purpose computer," and the claims are met by prior art systems that perform the recited function on such a computer.

5. Key Technical Contentions (Beyond Claim Construction)

• The petition's central technical contention was that the Patent Owner’s shift in its interpretation of "OID" in parallel litigation constituted a "changed circumstance" that justified this second petition. Petitioner contended that while the art in its first petitions met the broader OID construction, the newly asserted primary reference, Smith, explicitly discloses the "immutable" and "persistent" OIDs that the Patent Owner now argued were required. This strategic realignment was intended to neutralize the Patent Owner's new non-infringement theory and simultaneously strengthen the invalidity case.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and cancellation of claims 16-18, 24-29, 46-48, and 54-59 of the ’775 patent as unpatentable.