Tony Mason
Technical consulting and expert witness

Technical expert testimony in software and storage-systems litigation, from someone who spent twenty-two years building the systems these cases turn on. Patent, trade-secret, and software-defect matters, tested through deposition, trial, and appeal.

Twelve issued US patents, co-author of lex & yacc and Windows NT Device Driver Development, a 2025 PhD from UBC. Testifying and consulting engagements since 2003 across US federal district courts, the British Columbia Supreme Court, USPTO and PTAB proceedings, and an international matter. The technical reach covers patent claim construction in storage and data systems, trade-secret source-code analysis, software defect and functionality assessment, and digital forensics, with an emerging line in LLM-related litigation grounded in active research on AI reliability.

Technical scope

The cases that fit are the ones where the dispute turns on how a system actually works, and where the fact-finder needs that explained without being misled and without being condescended to.

File systems and storage internals
Three decades inside file systems and storage, from the Episode file system at Transarc through two decades of Windows file system filter work. This is the substrate most software and storage patents are written over.
Operating-system kernel and driver architecture
Windows kernel and driver internals at the level required to author the standard reference on the subject and to teach it to practicing engineers.
Trade-secret and source-code analysis
Code comparison across languages, abstract-syntax-tree analysis, and metadata timing analysis, used to establish or to rebut the claim that one codebase derives from another.
Patent claim construction and infringement analysis
Reading claims against accused systems in storage, backup, and data technology, including claim-construction testimony at a Markman hearing and background analysis for inter-partes review.
Software quality, functionality, and defect assessment
Assessing whether software does what it was specified to do, and whether it was built in a workmanlike manner, for defect and breach-of-contract matters.
Digital forensics and file-system metadata
File-system and photo metadata, deletion semantics, and what storage artifacts do and do not prove, including the distinction between genuine evidence of tampering and ordinary file-system behavior.
LLM systems and AI agent infrastructure
An emerging area: the reliability and failure modes of large language model systems, grounded in active 2026 research rather than secondhand familiarity.

On the record

Many qualified people testify. Two engagements are worth stating in full, because each cleared a bar that testimony by itself does not.

Elmagin Capital LLC v. Chao Chen
U.S. District Court, E.D. Pennsylvania; affirmed, U.S. Court of Appeals for the Third Circuit

Retained for the defendant in a trade-secret dispute. The matter went to a jury, which returned a verdict for the client; the verdict was upheld on appeal by the Third Circuit. I was cited by name in both the trial court's decision and the appellate opinion. An appellate court names a testifying expert only when the testimony was central enough to the trial record to bear on the reasoning under review.

Cent Holdings v. Wolfram Research
U.S. District Court, N.D. Alabama

Retained for the plaintiff in a trade-secret dispute. Opposing counsel moved to exclude my testimony; the court, applying the Daubert standard, found my qualifications and methodology admissible. The same engagement included an in-court Science Day tutorial, educating the trial judge on data provenance before substantive rulings.

Engagement record

A representative record of concluded engagements. Where a public-record filing or court decision exists, the case is listed by name with the filing linked, because the record is verifiable and the reader is owed the chance to verify. Where no public filing exists, the engagement is listed in anonymized form.

On the public record

Each engagement below has a filing or court decision on the public record. The linked documents are the actual filings or opinions; counsel can confirm them directly via PACER, the PTAB portal, or published appellate reporters.

  • O'Brien v. Microsoft 2024
    U.S. District Court, Western District of Washington, No. 2:19-cv-01625-RAJ
    rule 11 background report; amended complaint declaration; ipr declaration
  • Elmagin Capital LLC v. Chao Chen, et al. 2022
    U.S. District Court, Eastern District of Pennsylvania, No. 2:20-cv-02576-TJS
    U.S. Court of Appeals for the Third Circuit (upheld trial verdict)
    expert report; deposition; trial testimony; cited by name in trial decision; cited by name in appellate decision
  • UAB Tesso LT v. Luminati Networks LTD 2022
    Vilnius District Court, Vilnius, Lithuania
    rebuttal report
  • Las Vegas Skydiving, LLC v. Groupon, Inc. 2021
    U.S. District Court, District of Nevada, No. 2:18-cv-02342-APG-VCF
    declarations; deposition
  • St. Jude Medical, Inc. v. Volcano Corp. 2013
    U.S. District Court, District of Delaware, No. 12-441
    expert report; deposition; trial preparation
    • IPR Exhibit 1002 · IPR declaration; underlying matter reached the Federal Circuit on IPR one-year-bar timing
  • Legato Systems Inc. v. Network Specialists, Inc. 2005
    U.S. District Court, Northern District of California, San Jose Division, No. C03-02286 JW
    expert report; deposition; markman hearing testimony

Additional engagements

Concluded matters without a public-record filing, listed by dispute type, jurisdiction, and the work performed. Some were resolved before disclosure; some were non-testifying engagements where the work product was not filed. The named record for these is available to retaining counsel and their staff on request.

  • Employment contract / patent ownership dispute 2024
    King Cty. Super. Ct. (Wash.) · Opinion letter; testimony
  • Trade secret misappropriation 2024
    N.D. Ala. · Declaration; Daubert challenge survived; In-court Science Day tutorial
  • Trade secret misappropriation 2023
    W.D. Mo. · Expert report; deposition
  • Trade secret misappropriation 2020
    S.D.N.Y. · Evidentiary review for expert report
  • Patent infringement (storage technology) 2019
    D. Del. · Background research for IPR filing

Patents

Twelve issued US patents. They address the four things essentially every file has, its contents, its size, its name, and its timestamps, together with the deadlock-prevention infrastructure required to modify them safely. Each is linked to its public record.

  • US 11,720,529 Methods and Systems for Data Storage
    Continuation of 9,830,329; rights assigned through the Open Invention Network to IBM.
  • US 9,830,329 Methods and Systems for Data Storage
    Tunnels cache-coherency requests through an intermediate protocol that does not support them, by wrapping them in pass-through IOCTL calls.
  • US 9,600,486 File System Directory Attribute Correction
    Extends the file-attribute correction of 8,903,874 to the Windows attribute cache.
  • US 9,535,759 Work Queue Thread Balancing
    A dynamic thread pool that scales within bounds, trims when idle, and exposes cross-component deadlock detection.
  • US 8,990,228 Arbitrary Data Transformation
    Extends 8,521,752 to file data that both changes size and is spread across multiple storage layers.
  • US 8,903,874 File System Directory Attribute Correction
    Corrects the wrong size, name, or timestamps a host file system reports for a file carrying hidden embedded structure.
  • US 8,539,228 Managing Access to a Resource
    Embeds access controls inside a file, demonstrated by adding per-file access lists to the FAT file system.
  • US 8,521,752 Arbitrary Data Transformations
    The single-machine form of the embedded log-structured storage technique; held distinct from 7,949,693 after a PTAB hearing.
  • US 8,024,433 Managing Application Resources
    Lets a single binary file present different content depending on the client that opens it, collapsing per-configuration packaging.
  • US 7,949,693 Log-Structured Host Data Storage
    An embedded log-structured file system inside a single file, enabling transparent client-side encryption and compression with recoverable, in-place conversion.
  • US 7,809,897 Managing Lock Rankings
    Companion to 7,512,748; uses checksums to catch locks modified under a read lock or outside a write lock.
  • US 7,512,748 Managing Lock Rankings
    Programmatically verifies that a lock hierarchy is observed in complex systems, catching deadlock-order violations even across callbacks.

Books and technical writing

Co-author of three reference works, on compiler tools, on Windows driver development, and on Windows file system internals, and, across two decades, author of more than forty articles in OSR's technical journal The NT Insider.

  • lex & yacc
    O'Reilly & Associates, 1990
    Reference work on the UNIX parser generator tools lex (lexical analyzer) and yacc (parser generator). Standard reference for compiler-construction courses and practitioners; long-standing presence in O'Reilly's catalog.
  • Windows NT Device Driver Development
    New Riders, 1998
    Reference work on Windows NT kernel-mode device driver development, co-authored with OSR co-founder Peter Viscarola. Long-standing reference for driver development on Windows. Pattern-match credential for readers inside the Windows kernel ecosystem.
  • Windows NT File System Internals (OSR Classic Reprints)
    OSR Press, 2006
    Reprint of Rajeev Nagar's seminal Windows NT File System Internals, with TM as co-author on the OSR Press reissue. The original text is a foundational reference on Windows file system architecture.
  • The NT Insider: 40+ articles (1996-2017)
    OSR Press, 1996-2017
    Cumulative technical writing in The NT Insider on Windows internals, file systems, kernel debugging, and driver development across 21 years of OSR-era expertise. Aggregate entry; specific articles surfaced individually only where pattern-match-valuable.

Research relevant to AI litigation

Current research concerns the reliability of large language model systems: six 2026 arXiv preprints on topics including prompt-interference detection, epistemic observability, and demand paging for context windows. For litigation involving LLM behavior, agent-state failures, or AI reliability claims, that work is the technical foundation rather than secondhand reading. The full research record is at fsgeek.ca.

Retaining me

A first conversation establishes whether the matter is within my competence and free of conflict. That conversation is not billed.

Jurisdictions
Engagements to date span US federal district courts, a federal court of appeals, the British Columbia Supreme Court, USPTO and PTAB