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Stuart H. Sostmann Named Managing Attorney of Marshall Dennehey’s Pittsburgh Office

September 3, 2024

Stuart H. Sostmann, shareholder and co-chair of Marshall Dennehey’s Construction Injury Litigation Practice Group, has been named Managing Attorney of the the firm’s Pittsburgh office. He inherits the position from Scott G. Dunlop who served in the role for almost 30 years and will retire at the end of the year. Sostmann has served as Assistant Managing Attorney of the Pittsburgh office since 2023.

Marshall Dennehey’s Pittsburgh office is the firm’s third largest, following Philadelphia and Mount Laurel, NJ. The office houses 39 attorneys who practice in the areas of casualty, professional liability, health care and workers’ compensation litigation. In addition to providing counsel in Western Pennsylvania, a number of the office’s attorneys are barred in West Virginia and represent clients in its state and federal district courts. 

“Stu is a true leader who is committed to his work, his colleagues and to the firm’s culture and success,” said G. Mark Thompson, Marshall Dennehey’s President & CEO. “An outstanding trial lawyer, he serves as the Casualty Supervisor of the office, is a member of our Diversity, Equity & Inclusion Committee, and is a former president of the Pennsylvania Defense Institute. For the past year, he has worked closely with Scott, and we are fully confident he will maintain Scott’s high standards taking the office into the future.” 

Sostmann joined the firm in 1998. With over two decades of experience as a litigator, he has successfully tried numerous  cases to verdict in both state and federal courts. From routine matters to high-exposure cases, he concentrates his practice in construction litigation, product liability, premises liability, auto liability, marine liability, dram shop and commercial litigation. As the Casualty Litigation Supervisor, he ensures the office’s casualty cases are handled promptly, professionally and effectively.
 
In addition to the Pennsylvania Defense Institute (PDI), Sostmann is a member of the Allegheny County Bar Association and the Academy of Trial Lawyers of Allegheny County. He is a graduate of the University of Pittsburgh and the University of Pittsburgh School of Law. 
 

Stuart S

Firm Highlights

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Result

Summary Judgment Secured for Life Insurance Agent

Result

Summary Judgment Secured, Preserving $750,000 in Coverage for Insured in Major Trucking Liability Dispute

Ray Freudiger and Michael A. Roberts (both of Cincinnati) successfully obtained summary judgment on behalf of their client in a coverage dispute arising from a May 19, 2022, motor vehicle accident. A permissive driver operated a box truck for an interstate trucking company and caused severe injuries to two tort victims. Prior to the accident, the insured had procured a commercial auto policy for the trucking company with stated limits of $1,000,000. Following the accident, the insurer initiated a declaratory judgment action asserting that only reduced bodily injury limits of $25,000/$50,000 applied and later counterclaimed, alleging it would not have insured the driver had he been properly submitted for approval under the policy. After extensive discovery, briefing, and oral argument, the court rejected the insurer’s attempt to shift responsibility for the $750,000 in coverage it was legally required to provide for permissive drivers under Ohio law, granting summary judgment in favor of the insured and preserving $750,000 in liability exposure.

Event

Pennsylvania Appellate Update 2025-2026

On August 21, 2026, Casey will serve as a panelist for the live webcast program, “Pennsylvania Appellate Update 2025-2026” presented by the Appellate Advocacy Committee of the Pennsylvania Bar Association and Pennsylvania Bar Institute. The program is divided into three parts—Criminal, Civil, and Administrative. Casey will serve as a panelist for the Civil portion, along with Christina McKinley of Blank Rome, Ben Baer of Injury Law Partners, John Masslon of Keller Postman, Jonathan Bruno of Bruno Litigation LLC, and moderator, Ezza Ahmed of Buchanan Ingersoll.  Registration and more information: https://www.pbi.org/product/pennsylvania-appellate-update-2025-2026/

Marshall Dennehey Announces 2026 Ohio Super Lawyers and Rising Stars

News

Marshall Dennehey Announces 2026 Ohio Super Lawyers and Rising Stars

Jason Banonis Holds PDI Attorney of the Year Award with the PDI President

News

Jason Banonis Named Attorney of the Year by the Pennsylvania Defense Institute

Thought Leadership

A Unified, Single Claim for Damages Requires Apportionment in a Joint Proposal: What the Decision in 'Trace Elements' Means for Property Insurance Claims

Kimberly and Seth, shareholders in the Insurance Services Practice in our Fort Lauderdale office, break down the Florida Supreme Court's decision in 'Trace Elements v. MacKensen' and what it means for property insurance claims in the state. Read the article here.

blue facade of a hospital sign against blue sky

Result

Defense Verdict in Complex Medical Malpractice Trial

Thought Leadership

Appellate Division Affirms Dismissal of Legal Malpractice Counterclaim Against Martin Law Firm

In Martin v. Loury, 2026 N.J. Super. Unpub. LEXIS 1617 (App. Div. July 15, 2026), Martin Law Firm represented Kirk Loury in an employment matter Mr. Loury filed against his former employer, Concord Equity Group Advisors LLC (“Concord”). The allegations included, among other things, that Loury was not fairly compensated for his employment with Concord. After a bench trial finding in Loury’s favor, the Appellate Division remanded this matter in February 2016 for a second trial. During the second trial, Concord CEO, Lee Argush, testified to lower compensation estimate than first trial. On remand, the second trial judge awarded Mr. Loury the same damages as the first judge, finding Mr. Argush not credible. After the findings during the second trial, Martin Law Firm filed an action against Mr. Loury to recover legal fees and costs of representing Mr. Loury in a second bench trial and Mr. Loury filed a counterclaim against Martin Law Firm for legal malpractice, alleging he should have received an even higher award in the second bench trial. In this allegation, Mr. Loury, through his expert, claimed that Martin Law Firm should have recalled Mr. Loury to the stand to rebut Mr. Argush’s testimony to allege an alternative theory of damages. Mr. Loury’s expert admitted that the second judge already rejected Mr. Argush's theory and accepted Loury's damages theory. The trial court barred Mr. Loury’s expert and dismissed Loury's counterclaim with prejudice before convening the collection trial, and the jury ruled in Martin Law Firm’s favor. Mr. Loury appealed the trial court's pretrial rulings barring his liability expert from testifying in support of his legal malpractice counterclaim, denying his motion for summary judgment on that counterclaim, and denying his motion to amend his counterclaim by adding attorney Joseph A. Martin as a codefendant. In affirming the trial court’s decision, the Appellate Division held that the trial court properly excluded Loury’s expert testimony in the counterclaim against Martin Law Firm because the expert could not explain how calling Loury as a rebuttal witness would have increased damages when the second judge already rejected Mr. Argush's testimony and accepted Loury's damages theory, making the expert’s causation opinion speculative. The Appellate Division also held that the trial court properly denied Mr. Loury's summary judgment motion on his malpractice counterclaim because reasonable minds could differ on whether Mr. Martin's alleged failures would have changed the second judge's damages award, given the judge already found Mr. Argush not credible, creating genuine factual disputes precluding summary judgment. Also, the Appellate Division held that the trial court properly denied Loury's May 2023 motion to add Joseph Martin individually because the statute of limitations expired in February 2022, six years after the 2016 appellate remand when Mr. Loury incurred new legal costs, and relation back did not apply because Mr. Loury knew Mr. Martin's identity throughout and strategically chose to sue only Martin Law Firm in his 2019 counterclaim.

Portrait of Carolyn Schweizer, with text below: Philadelphia Office Managing Attorney

News

Marshall Dennehey Names Carolyn Schweizer New Philadelphia Office Managing Attorney

Thought Leadership

Fla. Workers' Comp Physician Dispensing Ruling Could Produce New Legislative Fight

In a significant decision issued on February 25, 2026, the First District Court of Appeal (DCA) ruled in Publix Super Markets, Inc., et al. v. Department of Financial Services, et al., 430 So. 3d 252 (Fla. 1st DCA 2026), that while injured workers have an absolute right to choose their own pharmacy or pharmacist, that right does not extend to physicians who dispense medications directly to their patients.  Read Blake's article in Insurance Journal: https://www.insurancejournal.com/news/southeast/2026/08/05/880229.htm.