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  • Sirena Castillo
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Sirena Castillo

Castillo_Sirena_New-Bio-Template-730-x-730

Partner and Director of Pro Bono

Contact
  • scastillo@manatt.com
  • Phone: 310.312.4336
  • Download vCard
  • Los Angeles
Bar Admissions
  • California
Education
  • University of Southern California Law School, J.D., 2008

    Georgetown University, M.A., 2002

    Georgetown University, B.S., 2002

    St. Petersburg State University, Certificate of Completion, 1999

Services
  • False Claims Act
  • Health Care Litigation
  • Investigations, Compliance and White Collar Defense
  • Litigation
  • Pro Bono
  • Profile
  • Experience
  • Speaking Engagements
  • Honors & Awards
  • Memberships
  • Publications
Profile

Profile

Sirena Castillo is a litigation partner in the investigations and white collar defense practice and also serves as the firm’s director of pro bono. She is resident in the Los Angeles office. 

Sirena’s litigation practice focuses on representing banks and other corporate entities during criminal investigations and complex civil litigation, with an emphasis on representing foreign entities in U.S. government investigations.

As Manatt’s director of pro bono, Sirena manages firm pro bono matters and develops the firm’s pro bono and community partnerships nationwide. She also maintains her own active docket of pro bono cases focused on immigration matters. Sirena’s work includes leading the pro bono team representing a class of abused, abandoned or neglected children in California seeking Special Immigrant Juvenile Status (SIJS) protections, and representing asylees before USCIS and in Immigration Court.

Within the firm’s investigations and white collar defense practice, Sirena has represented a wide variety of clients in state and federal courts, including clients in the health care, banking and insurance industries. Her white collar defense practice includes the representation of banks and corporations at all phases of government investigations, including responding to grand jury subpoenas and civil investigative demands. She also conducts internal investigations, both internationally and domestically, for banks and corporate entities in response to allegations of misconduct or to government inquiries. She has experience defending entities in a wide variety of white collar criminal matters, regulatory enforcement matters, internal investigations, and False Claims Act actions.

Experience

Experience

Lead counsel representing a class of abused, abandoned or neglected children in California seeking Special Immigrant Juvenile Status (SIJS) protections.

Representing a leading medical supplier in connection with a False Claims Act investigation by the Southern District of New York.

Representing a foreign financial institution in connection with a U.S. Department of Justice Offshore Tax Compliance investigation across several international jurisdictions.

Lead associate on several internal investigations for a large teaching hospital regarding potential False Claims Act violations.

Lead associate representing an oncology practice in a criminal investigation related to billing practices.

Member of the defense team representing a health insurer in a complex multiyear contract dispute with a hospital system.

Member of the defense team representing ticketing companies in a consolidated putative class action alleging deception in online sale of tickets.

Speaking Engagements

Speaking Engagements

Speaker, “Recognizing Federal Procurement Fraud: An Overview and Practical Insights,” Virginia Procurement Technical Assistance Center (Virginia PTAC), November 19, 2020.

Speaker, “Federal Procurement Fraud Overview and Practical Insights,” Northern California Procurement Technical Assistance Center (Norcal PTAC), October 22, 2020.

Speaker, “Creating Change—The Public and Private Sector Attorneys Transforming Law and Policy Through Advocacy,” Women Lawyers Association of Los Angeles, June 24, 2020.

Honors & Awards

Honors & Awards

The Best Lawyers in America, 2022–2024

California Lawyer Attorney of the Year (CLAY) Award 2020, Daily Journal

Public Counsel Law Center’s Pro Bono of the Year 2011, Immigrants’ Rights Project

Memberships

Memberships

Admitted to practice in the state of California

Admitted U.S. District Court for the Central District of California

Admitted U.S. District Court for the Northern District of California

Admitted U.S. District Court for the Eastern District of California

Admitted U.S. Court of Appeals for the Ninth Circuit

Member, American Bar Association

Member, Association of Pro Bono Counsel

Member, Women’s White Collar Defense Association

Member, Lawyers’ Committee for Civil Rights of the San Francisco Bay Area

Access to Justice Editorial Advisory Board, Law360, 2022-23

Publications

Publications

Quoted, “Firms help small businesses struggling through pandemic,” Daily Journal, December 7, 2021.

Quoted, “Going to Bat for Immigrant Kids Brings Broader Impacts on Humanitarian Relief,” Daily Journal, May 13, 2020.

"Associate Perspective: What I Wished I Learned in Law School," California Litigation, Vol. 25, No. 1, 2012.

Sirena in the News

  • 09.12.23

    Manatt Obtains Asylum for Mexican Single Mother Client

    A Manatt team successfully secured asylum for a single mother from Mexico, prevailing in a hearing before the Santa Ana Immigration ...

  • 09.01.23

    Nine Manatt Professionals Named to Law360’s 2023 Editorial Advisory ...

    Nine of Manatt’s professionals were named to various 2023 Law360 Editorial Boards, which provide insight on important legal issues to the pub...

  • 08.17.23

    82 Manatt Attorneys Named to 2024 Best Lawyers Guide

    Eighty-two Manatt attorneys have been named to the 2024 edition of Best Lawyers in America, which recognizes the nation’s leading lawyers eac...

  • 07.10.23

    Manatt Obtains Asylum for LGBTQIA+ Jamaican Client

    A Manatt team successfully secured asylum for an LGBTQIA+ Jamaican man after an eight-year process before the United States Citizenship and ...

Show More


Sirena's Newsletters

  • 02.07.22

    The Fourth Circuit Raises the Bar for Proving Scienter Under the ...

    On January 25, 2022, the U.S. Court of Appeals for the Fourth Circuit issued an important opinion for companies trying to navigate the complex ...

  • 08.20.20

    California Supreme Court Provides Seven-Factor Test for Motions to ...

    On August 13, 2020, the Supreme Court of California issued its decision in Facebook, Inc. v. Superior Court (Lance Touchstone), S245203, which ...

  • 03.28.13

    BSA Compliance Fails, Go to Jail

    For many years the government has encouraged directors and officers of corporations to ensure that they have robust compliance programs to detect and ...



Sirena's Events and Webinars

  • 06.30.20

    Risky Business: Federal Procurement Fraud in a COVID-19 World

    Federal contractors weren’t excluded from the huge federal funding initiatives rolled out to defeat COVID-19 and its impact. Whether under the ...

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