Brian K. Mahanna

Brian K. Mahanna provides strategic counsel to clients facing high-profile and complex investigations, corporate crises, regulatory scrutiny and other significant challenges, particularly when law and public policy converge. With years of state and local government experience—including at the head of one of the nation’s largest and most active state attorney general’s offices, and as senior advisor to the mayor of New York—Mr. Mahanna is uniquely positioned to advise and assist clients with complex regulatory issues at all levels of government. His insights have become especially valuable as state and local governments, particularly in the tristate area, lead the response to COVID-19.

As chief of staff and deputy attorney general in the Office of the New York State Attorney General, Mr. Mahanna was responsible for the office’s operations and served as the primary liaison to the governor’s office, the state legislature, state agencies and other state attorneys general, including on complex multi-state investigations and litigation. He also supervised all major civil, regulatory and criminal cases, investigations, legal positions and initiatives for a state at the center of the nation’s financial sector and other important industries and managed the Executive Division’s special counsels and the communications, data analytics, legislative and intergovernmental affairs departments. He adds this experience and strategic insight to WilmerHale’s robust State Attorneys General Practice joining lawyers who are well known and respected among the AG ranks and who have handled matters on behalf of clients in 47 states, as well the District of Columbia and US Virgin Islands, and effectively coordinated and represented companies in multistate AG investigations.

Before joining the Office of the New York Attorney General, Mr. Mahanna was in private practice, working on complex civil and criminal matters, with a focus on municipal and state government-related proceedings. He also served as senior adviser to former New York City Mayor Michael Bloomberg and as chief of staff and counsel to the deputy mayor for operations. In this role, Brian managed the operations of many of the city’s law enforcement and regulatory agencies.

Mr. Mahanna’s state and local government experience has made him a sought-after advisor on COVID-19 response, as governors and mayors have rapidly issued orders constraining clients’ business activities and state attorneys general probe allegations of price-gouging, fraud, and violations of state and local work-from-home orders. Since the pandemic began, he has advised clients across industries on how to interpret and respond to these orders as well as how to prepare for challenges ahead.

In both the public and private sectors, Mr. Mahanna has litigated across multiple jurisdictions and overseen highly publicized corporate investigations and white collar cases. He also advises companies facing public controversies in multiple arenas, such as when state attorneys general and other state regulators launch investigations along with Congress and federal agencies. His extensive policy and litigation experience give him a deep understanding of how government agencies approach issues within their purview and critical insight into the regulatory frameworks that govern his clients’ industries. He possesses the specific skillset needed to address the wide-ranging and complicated legal and reputational challenges presented by the increasingly commonplace investigations, litigation and enforcement actions launched by state attorneys general or other state and local regulators in areas as diverse as consumer privacy and data security, sports gaming, broadband, alternative lending and crypto products, and non-traditional modes of transportation.

Professional Activities

Mr. Mahanna is a trustee of the Citizens Budget Commission of New York.

  • COVID-19: State and Local Law Enforcement Target Price Gouging Practices

    In the wake of the coronavirus (COVID-19) outbreak complaints of “price gouging” have proliferated. State attorneys general and local law enforcement agencies are acting—issuing cease and desist letters, commencing investigations, or even effecting arrests—in response to these complaints.

    April 20, 2020
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  • State Attorneys General Practice Group

    Companies engaged with state attorneys general (AGs) face formidable challenges and a range of reputational, practical and legal considerations. Our group draws on the firm’s strength across the varied areas of state AG enforcement authority coupled with deep-seated crisis management experience to make us a leader in this space. 

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  • COVID-19 Presents Existential Legal and Regulatory Challenges for Long Term Care Facilities

    Brian Mahanna and co-authors address legal issues, risks and challenges long-term care facilities face as a result of the COVID-19 pandemic. 

    October 1, 2020
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Biden Administration Resource Center

Read our latest insights on the potential global influence of the Biden Administration.

COVID-19: New York Implements New “Winter Plan” Micro-Cluster Strategy for Coronavirus Restrictions

Client Alerts


  • COVID-19 Response

    Represent major national distributor of personal protective equipment in price gouging investigation.

    Counsel over a dozen companies, across a broad range of industries, regarding state and local executive orders and other regulatory and legislative responses to the coronavirus (COVID-19) pandemic.

  • State Regulatory Investigations

    Represent a technology company in an investigation by a state banking and insurance regulator regarding its advertising policies.
  • Comprehensive Strategic Counsel

    Devise a nationwide public policy, advocacy and litigation strategy for Period Equity, a nonprofit advocacy organization dedicated to eliminating the New York state sales tax on menstrual products, known as the “Tampon Tax.”
  • State AG Investigations

    Represent an online software company in consumer protection investigations conducted by more than a dozen state attorneys general.
  • State AG Engagement

    Advise a consumer services company concerning proactive engagement with state attorneys general regarding consumer protection issues.
  • Public Policy and Legislative Affairs

    Advised a sports gambling company concerning federal and state gaming and tribal gaming issues in connection with a sports gambling legalization campaign.

Insights & News


  • Education

    • JD, Yale Law School, 2009

    • BA, Political Science and Metropolitan Studies, New York University, 2003

      magna cum laude
  • Admissions

    • New York

    • US District Court for the Eastern District of New York

    • US District Court for the Southern District of New York

  • Government Experience

    • State and Local Government

      Chief of Staff and Deputy Attorney General, New York
    • State and Local Government

      Senior Advisor to the Mayor, Office of the Mayor of New York City