New York attorney record · Judicial Dept 1
Thomas D. O'Brien
Columbia University alumna, admitted to the New York bar in 2003, registered office in Sunnyvale, CA. This established record's status, address, and registration history come straight from the NY Office of Court Administration.
- 2003
- Admitted
- 23
- Years in bar
- 4154688
- NY reg #
The record in one line
Thomas D. O'Brien appears in the New York attorney register with a current status of "Due to reregister within 30 days of birthday", on record since 2003 - an administrative designation rather than discipline, but confirm current standing with the state bar.
- 23 yrs
- since first admission to the bar
- Pending-renewal
- current bar status: "Due to reregister within 30 days of birthday"
- Law school
- Columbia University
Data updated May 2026
What this profile tells you
Bar status & tenure
Thomas D. O'Brien is registered as bar number 4154688 with the New York bar authority, carrying a current status of "Due to reregister within 30 days of birthday", a routine periodic-renewal reminder, not discipline. Registration is recorded within Judicial Department 1, the appellate division overseeing this attorney's home district.
Practice context & education
Practice address is listed under Illumio, Inc., located in Sunnyvale, CA, ZIP 94085. Educational background: COLUMBIA UNIVERSITY.
State context & due diligence
A "Due to reregister within 30 days of birthday" status falls outside the New York bar's active cohort for now. The breakdown below shows what share of the register that represents.
How Thomas compares to fellow Columbia University alumni
Among the 1,236 Columbia University graduates in the New York register, Thomas D. O'Brien is longer-tenured than 12% - a school-cohort view of experience, alongside the statewide one above.
23 years vs. Columbia University alumni
Years since admission - 1,236 NY-registered alumni of this school
23 Top 88% higher than 12% of 1,236 fellow alumni
Each bar is a band; taller bars hold more fellow alumni. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source NY Office of Court Administration, Attorney Registration · May 2026
The 2003 admission class today
Of the 8,250 attorneys admitted to the New York bar in 2003, 81% are still "Currently registered" today, above the statewide average across all admission years.
Professional Details
- Status
- Due to reregister within 30 days of birthday
- Registration Number
- 4154688
- Year Admitted
- 2003 (23 yrs · senior)
- Judicial Department
- 1
- Next Registration
- Dec 2025
Location & Contact
- Company
- Illumio, Inc.
- City
- Sunnyvale, CA
- ZIP Code
- 94085
- Phone
- (646) 675-7019
Education
COLUMBIA UNIVERSITY
Status Distribution Across the New York Bar
Thomas D. O'Brien's current status, "Due to reregister within 30 days of birthday", places this record outside the 66.2% of the 429,620-attorney New York register currently marked active.
Full statewide breakdown & source note
Source: NY Office of Court Administration, Attorney Registrations. Status counts reflect the latest reporting cycle. Bar status confirms registration only; it does not imply competence, specialty fit, or freedom from complaints.
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Thomas D. O'Brien is currently listed as "Due to reregister within 30 days of birthday", treat that as a registration fact to confirm, not a verdict on quality.
Frequently Asked Questions
Where is Thomas O'Brien licensed?
Thomas O'Brien is licensed to practice law in New York.
When was Thomas D. O'Brien admitted to the bar?
Thomas D. O'Brien was admitted to the bar in 2003.
Where did Thomas D. O'Brien go to law school?
Thomas D. O'Brien attended COLUMBIA UNIVERSITY.
What company does Thomas D. O'Brien work for?
Thomas D. O'Brien is associated with Illumio, Inc. in Sunnyvale, CA.
Is Thomas D. O'Brien in good standing?
Not currently, Thomas D. O'Brien's listed status is "Due to reregister within 30 days of birthday", not active standing. Confirm current status with the state bar.
Sourced from the NY Office of Court Administration, informational only, not legal advice. Full disclosure.
Read our methodology - how this data is sourced, computed, and verified.