About Arnold & Porter LLP · Washington
Arnold & Porter LLP (legal entity Arnold & Porter Kaye Scholer LLP, doing business as Arnold & Porter) is one of the oldest and largest international law firms in the United States, founded in 1946 and headquartered in Washington, D.C. With more than 1,000 lawyers across 16 offices on four continents, the firm provides sophisticated regulatory, litigation, and transactional counsel to over half of the Fortune 100. It is widely recognized as a 'white-shoe' firm with landmark cases such as Gideon v. Wainwright in its founding-era portfolio and consistently top-tier rankings from Chambers USA, Chambers Global, and Best Lawyers.
Arnold & Porter traces its origins to 1946, when Thurman Arnold, a former Yale Law School professor and D.C. Circuit judge, and Abe Fortas, a future U.S. Supreme Court justice, established Arnold & Fortas in Washington, D.C. Paul A. Porter, a former chairman of the Federal Communications Commission, joined in 1947 and the firm became Arnold, Fortas & Porter. In 1965, after Fortas's appointment to the Supreme Court, his name was dropped from the firm. On January 1, 2017, Arnold & Porter combined with New York-based Kaye Scholer LLP to form Arnold & Porter Kaye Scholer LLP, a near-1,000-lawyer global firm that subsequently retired the 'Kaye Scholer' branding in public-facing materials while keeping the legal entity name. The firm represents more than half of the Fortune 100 across an integrated offering of regulatory, litigation, and transactional services spanning 40+ practice areas and industry groups. Its regulatory bench draws heavily on former senior U.S. and European government officials; its litigation practice includes former federal and state prosecutors; and its transactional teams serve clients in life sciences, financial services, technology, energy, and more. Pro bono work has been central since its founding—most famously Abe Fortas's representation of Clarence Earl Gideon before the U.S. Supreme Court in Gideon v. Wainwright—and the firm logged more than 100,000 pro bono hours in 2024, ranking among the top firms nationally for that work.
- In business
- 79 years (founded 1946)
- Owner
- Founded by Thurman Arnold and Abe Fortas in 1946 (as Arnold & Fortas); Paul A. Porter joined as name partner in 1947. Current firm leadership includes Co-Chairs Michael D. Daneker and Ellen Kaye Fleishhacker.
- Serves
- Global — U.S. offices in Washington, D.C. (headquarters), New York, Boston, Chicago, Denver, Houston, Los Angeles, Newark, Palo Alto (Silicon Valley), San Francisco, and Seattle; international offices in London, Brussels, Amsterdam, Frankfurt (historically; closed 2021), Shanghai, Seoul, and Beijing, plus a presence in China, Cuba, Europe, India, Japan, Korea, Latin America/Caribbean, and the Middle East.
Founding and History
Arnold & Porter traces its roots to 1946, when Thurman Arnold and Abe Fortas — both former Yale Law School professors — founded Arnold & Fortas in Washington, D.C. Paul A. Porter, former chairman of the Federal Communications Commission, joined in 1947, and the firm was renamed Arnold, Fortas & Porter. When Abe Fortas was elevated to the U.S. Supreme Court in 1965, his name was dropped from the firm — and the firm famously declined to re-admit him after his 1969 resignation from the bench. The 2017 combination with New York's Kaye Scholer LLP (itself dating to 1917) created Arnold & Porter Kaye Scholer LLP, a near-1,000-lawyer global platform; the firm has since retired the 'Kaye Scholer' branding from its public identity while keeping it in the legal entity name.
- Founded 1946 as Arnold & Fortas by Thurman Arnold and Abe Fortas
- Paul A. Porter joined 1947; renamed Arnold, Fortas & Porter
- Abe Fortas's name removed from firm in 1965 upon his Supreme Court appointment
- Merged with Kaye Scholer LLP on January 1, 2017; branded as Arnold & Porter thereafter
Practice Areas and Industries
Arnold & Porter organizes its work into three integrated service lines — Litigation, Regulatory, and Transactional — spanning more than 40 distinct practice areas and industry groups. Its regulatory bench draws on former senior U.S. and European government officials; its litigation practice includes former federal and state prosecutors; and its transactional teams serve clients across life sciences, financial services, energy, technology, and more. Industry depth includes life sciences & healthcare, financial services, telecommunications, energy & infrastructure, technology & media, transportation, consumer products & retail, chemicals, agribusiness, and tax-exempt organizations.
- Litigation: Commercial, Class Actions, Trials, Appellate & Supreme Court, White Collar Defense, Product Liability, Antitrust/Competition Litigation
- Regulatory: Antitrust/Competition, Environmental, Government Contracts, Life Sciences & Healthcare Regulatory, Privacy/Cybersecurity, National Security/CFIUS, Telecom/Internet/Media
- Transactional: Corporate & Finance, M&A, Capital Markets, Securitization, Bankruptcy & Restructuring, Real Estate, Tax, Private Client Services, Tax-Exempt Organizations
- Cross-border: International Arbitration, International Trade, Public International Law, Foreign offices in London, Brussels, Amsterdam, Shanghai, Seoul
Washington, D.C. Headquarters Office
The Washington, D.C. office at 601 Massachusetts Avenue NW is one of the oldest and largest in the firm and includes attorneys from all 40 of the firm's practices. The office houses the firm's renowned regulatory group, with many former high-ranking government officials advising on FDA, environmental, telecom, antitrust, and federal government matters. The Washington-based co-chair of the firm is partner Michael D. Daneker.
- Address: 601 Massachusetts Ave, NW, Washington, DC 20001-3743
- Phone: +1 202.942.5000 / Fax: +1 202.942.5999
- Includes representation from all 40+ firm practices
- Firmwide Co-Chair Michael D. Daneker is based here
Other U.S. Offices
In addition to Washington, Arnold & Porter maintains ten other U.S. offices across major commercial and financial centers, with its New York office being one of the largest at roughly 350 attorneys. The firm has steadily expanded its U.S. footprint, opening a Seattle office announced in 2025.
- New York — 250 West 55th Street, NY 10019; +1 212.836.8000 (~350 attorneys)
- Boston — 500 Boylston Street, 20th Floor; +1 617.351.8050
- Chicago — 300 North LaSalle Drive, Suite 3500; +1 312.583.2300
- Denver — 1144 Fifteenth Street, Suite 3100; +1 303.863.1000
- Houston — 811 Main Street, Suite 1800; +1 713.576.2400
- Los Angeles — 777 South Figueroa Street, 44th Floor; +1 213.243.4000
- Newark — One Gateway Center, Suite 1025; +1 973.776.1900
- Palo Alto / Silicon Valley — 3000 El Camino Real, Suite 500; +1 650.319.4500
- San Francisco — Four Embarcadero Center, 14th Floor; +1 415.471.3100
- Seattle — U.S. Bank Center, 1420 5th Avenue, Suite 1400; +1 206.288.0110 (announced July 2025)
International Offices
Arnold & Porter's global footprint spans Europe and Asia, supporting cross-border transactions, international arbitration, antitrust reviews, and trade-compliance matters. The Frankfurt office, however, was closed at the end of March 2021.
- London — Tower 42, 25 Old Broad Street, EC2N 1HQ; +44 (0)20 7786 6100
- Brussels — Avenue Louise 149, 1050 Brussels; +32 2 290 7800
- Amsterdam — Strawinskylaan 385, 1077 XX; +31 (0)20 809 7020
- Shanghai — Plaza 66 Building 2, #4306-4313, 1266 Nanjing Xi Rd; +86 (0)21 2208 3600
- Seoul — 20F, Concordian, 76 Saemunan-ro, Jongno-gu; +82 2 6744 2000
Pro Bono and Public Service
Pro bono has been a foundational value at Arnold & Porter since its founding — the firm represented Clarence Earl Gideon in Gideon v. Wainwright (1963), establishing the Sixth Amendment right to counsel in felony cases. Today the firm's pro bono work spans impact litigation, individual representation, regulatory/public-policy advocacy, and nonprofit counseling. The firm logged more than 100,000 pro bono hours in 2024, was ranked #2 nationally by Law360 in 2023, and has been named to Bloomberg Law's 2025 'Pro Bono Innovators' list. Its pro bono roster has included Afghan refugee asylum work (partnering with Catholic Charities of the Archdiocese of Galveston-Houston), representation of separated immigrant families, religious-liberties cases (including allowing a spiritual advisor at an Alabama execution), and wrongful-conviction matters such as the release of a man imprisoned 44 years.
- 100,000+ pro bono hours in 2024
- Law360 pro bono ranking #2 nationally (2023)
- Bloomberg Law 2025 'Pro Bono Innovators'
- Represented 90+ Afghan refugees in asylum matters in partnership with Catholic Charities of the Archdiocese of Galveston-Houston, Tahirih Justice Center, KIND, IRC, and others
- Landmark Gideon v. Wainwright representation (1963)
- Religious-liberties wins for death-row inmates' spiritual advisors
Rankings, Recognition and Awards
Arnold & Porter regularly earns top-tier recognition across the legal industry's leading directories. Chambers USA 2024 named it a 'Leading Firm' in 65 practice areas with 124 'Leading Individuals'; Chambers Global 2024 ranked it in 31 practice areas with 35 'Leading Individuals'; the 2024 edition of Best Lawyers' 'Best Law Firms' named it 'Law Firm of the Year' for Litigation – Environmental and International Arbitration – Commercial; and the firm has earned a 100% rating on the Human Rights Campaign Foundation's Corporate Equality Index. Vault ranks it #32 in its Law 100, #3 for Environmental Law, #6 for Products Liability, and #9 for Government Relations.
- Chambers USA 2024: 65 practice rankings, 124 leading lawyers
- Chambers Global 2024: 31 practice rankings, 35 leading lawyers
- Best Lawyers 'Law Firm of the Year' 2024: Litigation – Environmental; International Arbitration – Commercial
- HRC Corporate Equality Index: 100% rating
- Vault Law 100: #32 overall; #3 Environmental, #6 Products Liability, #9 Government Relations
Firm Values and Culture
According to the firm's 'About' page, Arnold & Porter stays true to four core values: providing exceptional client service, enhancing lives in its communities, prioritizing a collegial work environment, and fostering a diverse workplace through an unyielding commitment to inclusivity. The firm emphasizes interdisciplinary collaboration across its regulatory, litigation, and transactional practices and draws heavily on the public-sector experience of its lawyers.
- Core values: client service, community, collegiality, inclusivity
- Interdisciplinary, firmwide collaboration across all 40+ practice areas
- Heavy public-sector bench (former U.S. and European regulators and prosecutors)
Notable Cases and Clients
Beyond Gideon v. Wainwright, the firm's historic docket has included defense of clients during the McCarthy era and recent voting-rights cases. It has also represented more than 90 Afghan refugees and worked with the American Immigration Council and the National Immigrant Justice Center on behalf of immigrant families separated at the U.S. border in 2018. Its client base spans over half of the Fortune 100, with deep relationships across life sciences, financial services, technology, energy, and regulated industries.
- Gideon v. Wainwright (1963) — right to counsel
- Defense of individuals targeted during the McCarthy hearings
- Recent voting-rights litigation
- FTCA litigation on behalf of separated immigrant families (co-counsel with American Immigration Council and National Immigrant Justice Center)
- Serves more than half of the Fortune 100