About
Nathan Castellano focuses his practice on U.S. government contracts and grants, advising clients on litigation, investigations, compliance counseling, negotiation, and complex transactions. He brings deep experience navigating the intersection of public procurement and private enterprise, and is widely recognized for his thought leadership in the field.
Before joining the firm, Nathan held senior roles at two leading international law firms, where he built and led teams handling high-stakes disputes, internal investigations, transactions, and strategic regulatory matters for federal contractors and grantees.
Nathan clerked for the Hon. Jimmie V. Reyna of the U.S. Court of Appeals for the Federal Circuit and previously served in an advisory role at the World Bank.
He is a co-author of the leading treatise, Formation of Government Contracts (5th Edition), and he is a contributing author to The Nash & Cibinic Report. His accolades include recognition by Chambers USA as “Up and Coming” in Government Contracts (2025, 2026), Law360 Rising Stars (2023), and Best Lawyers: Ones to Watch (2021–2025).
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Additional Information
- Mergers & Acquisitions (M&A): Nathan supports transactional matters involving U.S. government contracts and federal funding, including due diligence, the novation process, and compliance support. Representative deals at Freshfields include:
- Advise ServiceNow on the $7.75 billion purchase of Armis, a cybersecurity company founded in Israel with significant U.S. contracting portfolio.
- Advise Amadeus on the €1.2bn proposed acquisition of IDEMIA Public Security.
- Advise Beazley plc, the leading specialty insurer, on its acquisition of kWh Analytics, Inc.
- Advise Altor (Altor Fund VI and Altor ACT I) on its acquisition of a majority stake in Evac Holding Oy from Bridgepoint.
- Compliance: Nathan helps companies understand and manage the compliance obligations that are tied to federal funding awards. He is experienced counseling a diverse range of clients—from established members of the defense industrial base to companies just entering the market for federal contracts and grants.
- Intellectual Property (IP): Nathan helps companies navigate the unique rules that govern IP rights in government contracts, grants, and other funding arrangements. This ranges from helping companies develop IP protection strategies, training personnel to implement those strategies, negotiating contract terms to protect IP, and resolving IP disputes with the government and third parties.
- Federal Circuit Appeals: As one of a select few government contracts lawyers in private practice to have clerked at the US Court of Appeals for the Federal Circuit, Nathan provides valuable perspective when clients appeal government contract matters to the Federal Circuit. Having represented contractors in several significant Federal Circuit appeals over the past decade, he has hands-on experience with the court’s relevant appellate procedures and local rules. Representative appeals include the following (prior to joining Freshfields):
- CACI, Inc.-Fed. v. United States, 67 F.4th 1145 (Fed. Cir. 2023)
- WellPoint Mil. Care Corp. v. United States, 953 F.3d 1373 (Fed. Cir. 2020)
- Cleveland Assets, LLC v. United States, 897 F.3d 1332 (Fed. Cir. 2018)
- PDS Consultants, Inc. v. United States, 907 F.3d 1345 (Fed. Cir. 2018)
- Oracle Am., Inc. v. United States, 975 F.3d 1279 (Fed. Cir. 2020)
- James v. Wilkie, 917 F.3d 1368 (Fed. Cir. 2019)
- Bid Protests: Nathan has successfully litigated high-stakes protests on behalf of clients ranging from the largest defense contractors and technology companies to small and veteran-owned businesses. He develops and implements sophisticated, multi-forum bid protest litigation strategies before the Government Accountability Office, United States Court of Federal Claims, federal district courts, and the Federal Circuit. Representative bid protest matters include the following (prior to joining Freshfields):
- Samsara Inc. v. United States, 170 Fed. Cl. 229, 232 (2024)
- mLINQS, LLC v. United States, No. 22-1351, 2023 WL 2366654 (Fed. Cl. Mar. 6, 2023)
- Trace Sys. Inc. v. United States, 165 Fed. Cl. 44 (2023)
- Medline Indus., Inc v. United States, 155 Fed. Cl. 522 (2021)
- Owens & Minor Distribution, Inc. v. United States, 154 Fed. Cl. 349 (2021)
- Blue Origin Fed'n, LLC v. United States, 157 Fed. Cl. 74 (2021)
- Space Expl. Techs. Corp. v. United States, No. 219CV07927ODWGJSX, 2020 WL 7344615 (C.D. Cal. Sept. 24, 2020).
- Space Expl. Techs. Corp. v. United States, 144 Fed. Cl. 433 (2019)
- Vigor Marine LLC, B-420955.2 , 2022 CPD ¶ 276, Oct. 31, 2022
- Oracle Am., Inc., B-420181, 2021CPD ¶ 278, Nov. 30, 2021
- Blue Origin Federation, LLC; Dynetics, Inc., B-419783 et al., 2021 CPD ¶ 265, July 30, 2021
- Mythics, Inc.; Oracle Am., Inc., B-418785 et al., 2020 CPD ¶ 295, Sept. 9, 2020
- Oracle Am., Inc., B-416657 et al., 2018 CPD ¶ 391, Nov. 14, 2018
- Contract Claims: In addition to guiding clients through the traditional Contract Disputes Act (CDA) process, Nathan specializes in non-traditional methods of dispute resolution. He has successfully litigated against the government in the U.S. Court of Federal Claims, federal district courtand employed alternative dispute resolution to resolve software licensing and copyright infringement claims with the Department of Defense.
- Negotiation: Nathan negotiates teaming agreements and subcontracts on behalf of prime contractors, subcontractors, and grant recipients alike. He has also advised clients through negotiation of negotiated Other Transaction Agreements (OTAs), Cooperative Research and Development Agreements (CRADAs), and Technology Investment Agreements (TIAs).
- Freedom of Information Act (FOIA): Nathan helps companies protect confidential and proprietary information that is shared with government entities. He develops compliance strategies to protect information before and during submission, helps train personnel to implement those strategies, and then advocates to ensure that information is not released in response to a FOIA request.
- Grants and Cooperative Agreements: Nathan is experienced counseling clients on a wide range of issues relating to federal grants and cooperative agreements, including: compliance obligations and strategies, subawards and contract negotiation, and dispute resolution.
Nathan Castellano
Counsel
Washington, DC Office
700 13th Street, NW
10th Floor
Washington, DC 20005-3960