Described as a “talented litigator” and “excellent tactician and advocate” by Chambers USA, Conor O’Croinin represents clients—ranging from individuals to law firms to Fortune 10 companies—in a broad array of complex commercial litigation matters, including cases involving novel public nuisance theories, attempts at corporate veil piercing, and allegations of fraud.
His clients have included campaign finance entities, as well as individuals and corporations appearing before the Office of the Maryland State Prosecutor, the Maryland Board of Elections, and the Federal Election Commission (FEC), as well as lawyers and law firms facing disqualification motions, malpractice actions, and other sensitive issues.
Conor also has experience representing clients in insurance coverage disputes and in white collar litigation.
Conor previously clerked for the Hon. Alan M. Wilner of the Court of Appeals of Maryland, and for the Hon. Beth P. Gesner of the U.S. District Court for the District of Maryland.
In 2004, Conor graduated with honor from the University of Maryland School of Law, and upon graduation was made a member of the Order of the Coif. He received a bachelor’s degree from the University of Maryland in 2000.
Experience
- Represents a national pharmacy chain in defense of thousands of suits by state and local governments to recover costs alleged to have been caused by the shipment and dispensing of prescription opioids.
- Represented a Maryland campaign finance entity.
- Represented a nationally recognized health system before the Maryland Health Care Commission in its efforts to obtain a certificate of need to open a liver transplant program.
- Represented an animal welfare organization in an insurance coverage dispute. The firm lost the case at trial, but obtained a complete reversal on appeal. The Court of Special Appeals held that the trial court should have entered judgment for the firm’s client. The Court of Appeals affirmed in a unanimous opinion.
- Represented several cardiologists who were accused by their former employer of violating covenants not to compete. Two of the matters settled before any significant motions practice, and the employer subsequently dropped the matter entirely as to a third cardiologist.
- Represented a real estate developer who originally sued his former partner in a contract dispute. The former partner filed a 19-count complaint against our client and the lawyers that represented him in the original litigation. The firm drafted a comprehensive motion to dismiss all counts, and shared it with opposing counsel before filing it with the court. Opposing counsel agreed to dismiss the entire lawsuit with prejudice.
- Entered our appearance on behalf of party against whom a multimillion dollar judgment was entered by a Maryland trial court. The prevailing party sought in excess of $4 million in attorney’s fees pursuant to a contractual fee-shifting provision. After a four-day bench trial, the Circuit Court awarded the prevailing party $0 in attorney’s fees in response to our argument that the prevailing party had been overcompensated by the original judgment. Although this ruling was reversed on appeal, the appellate court directed entry of an attorney’s fees award of only $1.4 million, based on the trial court’s alternative finding that the prevailing party was not entitled to several million dollars in legal fees.
- Assisted with a merits brief concerning Article III standing heard by the U.S. Supreme Court in October 2011. On the last day of the term, the Supreme Court dismissed the writ of certiorari as having been improvidently granted, thereby affirming the lower court’s ruling in our client’s favor.
- Represented senior officers and their corporation in connection with investigations by the Maryland State Prosecutor and the Federal Election Commission (FEC) concerning alleged campaign finance rules violations. Both matters settled, and the firm continues to provide advice to the corporation about the law of campaign finance.
Practice Focus
Education
- University of Maryland School of Law, J.D., with honor, 2004
- Order of the Coif
- Associate Editor, The Business Lawyer
- National Moot Court Team
- William P. Cunningham Award
- University of Maryland, B.A., 2000
Bar Admissions
- Maryland
- Pennsylvania (inactive)
Court Admissions
- U.S. Supreme Court
- U.S. Court of Appeals, Second Circuit
- U.S. Court of Appeals, Fourth Circuit
- U.S. Court of Appeals, Seventh Circuit
- U.S. Court of Appeals, Tenth Circuit
- U.S. District Court, District of Maryland
- U.S. District Court, Eastern District of Wisconsin
Clerkships
- Court of Appeals of Maryland
- U.S. District Court, District of Maryland
Professional Leadership
- Member, American Bar Association
- Member, Bar Association of Baltimore City
- Member, Pennsylvania Bar Association
- National Institute for Trial Advocacy (NITA) Advocate Designation
Recognitions
News & InsightZS Blog
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How one family’s ‘nightmare’ eviction could change Baltimore City law
January 2, 2026
| In the News
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Nearly Half of Zuckerman Spaeder Attorneys Receive The Best Lawyers in America® Recognitions, Including Several “Ones to Watch”
August 22, 2025
| Press Release
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Zuckerman Spaeder Continues to Grow Its Recognitions in the Latest Chambers USA Guide
June 5, 2025
| Press Release
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Political Activity, Lobbying Laws & Gift Rules Guide: Chapter 12, The Enforcement of Federal Campaign Finance Laws
March 7, 2025
| Publication
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Best Lawyers® Recognizes 40 Zuckerman Spaeder Attorneys, Including Three “Lawyers of the Year” and Seven “Ones to Watch”
August 15, 2024
| Press Release
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Baltimore, drug companies tussle in court over responsibility for city’s opioid crisis
August 6, 2024
| In the News
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4th Circuit Finds Baltimore Violated Evicted Tenants’ Due Process Rights
June 12, 2024
| In the News
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Appeals Court Upholds Ruling that Baltimore City Violated Evicted Tenants’ Constitutional Rights
June 11, 2024
| Press Release
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Chambers USA Ranks Half of Zuckerman Spaeder Partners in 2024 Edition
June 6, 2024
| Press Release
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42 Zuckerman Spaeder Attorneys, Including Six “Ones to Watch,” Recognized in 2024 Edition of The Best Lawyers in America
August 17, 2023
| Press Release