Cassidy Law PLLC is a boutique law firm committed to providing legal services to individuals and businesses as they navigate the complex laws and regulations that govern individual behavior and the behavior of businesses.

Cassidy Law provides legal services to clients as they interact with governments whether because they are facing criminal charges or are developing business with governments and providing goods and services to governments.  Cassidy Law strives to ensure that its clients have peace of mind and confidence regarding the outcome of their legal issues.



If you are under investigation; charged with a crime; a witness to possible illegal actions; subpoenaed to testify; required to produce documents for the government; or receive a letter from the government saying you are under investigation, Cassidy Law can assist you.

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If your business is under investigation; charged with a crime; has been subpoenaed to produce documents; or your employees have been subpoenaed, Cassidy Law can assist you.

Cassidy Law can also provide guidance on compliantly working with governments to include working with your business to establish or improve an ethics and compliance program so your business may proactively manage the risk of violating laws or making unethical decisions.

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Practice Areas Include:

Interacting with Government Officials and Employees

  • Lobbying
  • Political Activity
  • Gifts


  • Foreign Corrupt Practices Act
  • Federal, state and local anti-corruption laws

Federal Government Contracting

  • False Claims Act
  • Conflicts of Interest
  • Procurement Integrity

Ethics & Compliance

  • Establishing ethics and compliance programs

Internal Investigations

Criminal Defense

  • When arrested
  • Under Investigation
  • Subpoenaed

About Margaret Cassidy

Cassidy Law’s founding attorney, Margaret Cassidy develops authentic, collaborative relationships with her clients by listening to them and understanding their issues and challenges. Margaret’s experiences enable her to explain legal issues in a direct and straightforward manner and, to identify practical and accessible solutions to complex problems.

headshotA seasoned criminal litigator, Margaret is proficient in dealing with the criminal justice system. She has tried over a hundred jury and non-jury criminal cases to verdict and has been the lead attorney in a variety of criminal proceedings such as grand jury investigations, evidentiary motions, probation violation hearings, sentencing hearings, and plea negotiations.

In addition to criminal litigation experience, Margaret has counseled businesses on developing and executing effective ethics and compliance programs particularly when dealing with foreign, federal, state and local governments. She has provided guidance before and after legal issues have occurred on matters related to anti-corruption, the Foreign Corrupt Practices Act, ethics laws, the False Claims Act, political activity, government procurement, and conflicts of interest. Margaret has conducted internal investigations in numerous countries and has provided counsel to business leaders on how to remediate and resolve investigative findings.

Along with her dedication to the law, Margaret is also enthusiastic about teaching.   As a result, she has developed and conducted trainings and seminars for business executives, employees, fellow lawyers, and law enforcement professionals on topics as diverse as conducting investigations; implementing ethics and compliance programs; FCPA compliance; the False Claims Act; anti-corruption; conflicts of interest; lobbying; campaign finance; criminal law and procedure; and ethically interacting with governments.   As an adjunct professor, Margaret taught courses on business law and public speaking.

Active in her profession and in her community, Margaret is a member of the American Bar Association,  the Washington DC Bar, and the National Association of Criminal Defense Lawyers. She is the former Global Issues Forum Co- Chairperson for the Washington Metro Association of Corporate Counsel. Margaret serves on the board of the Washington DC Area Lawyers for the Arts.

Margaret received her undergraduate degree in Finance from Miami University in Oxford, Ohio, and her law degree from the University of Pittsburgh School of Law.  Upon her law school graduation, Margaret served as an appellate law clerk with the Ohio Court of Appeals.

Margaret is admitted to practice in Washington DC and Pennsylvania. She is also admitted to practice in Ohio and New York but is currently inactive in those states.

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head Cassidy Law PLLC
1425 K. Street, Suite 350
Washington, DC 20005
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