What do Erie Injury Lawyers mean when they refer to ‘case law’?

When Pennsylvania lawyers refer to “case law,” they are describing one of the two primary sources of law that govern civil disputes — the body of legal rules created by judges through their decisions in actual cases, as distinguished from statutes enacted by the legislature.

What Case Law Is

Case law — also called common law or judge-made law — consists of the written opinions issued by courts when they decide disputed legal questions. When a court resolves a legal issue in a particular way, that decision establishes a precedent that guides how similar issues should be decided in future cases. Over time, the accumulation of these decisions builds an elaborate body of legal rules covering nearly every area of civil and criminal law.

In Pennsylvania, case law is created by decisions of the Pennsylvania Supreme Court, the Pennsylvania Superior Court (which handles most civil appeals), the Pennsylvania Commonwealth Court (which handles cases involving government entities), and the various Courts of Common Pleas at the county level. Federal courts — including the U.S. District Court for the Western District of Pennsylvania, which covers Erie — also create case law that applies to federal questions and diversity jurisdiction cases.

How Case Law Interacts With Statutes

Statutory law — rules enacted by the Pennsylvania General Assembly or the U.S. Congress — provides one layer of legal authority. Case law provides another. When a statute exists on a topic, courts interpret and apply it through their decisions, and those interpretive decisions become part of the case law. When no statute governs a particular issue, courts fall back on common law principles that have been developed through decades or centuries of judicial decisions.

In personal injury law, for example, many of the fundamental rules — what constitutes negligence, how damages are calculated, when a landowner owes a duty to a visitor — are rooted in Pennsylvania common law developed through court decisions over more than a century, supplemented by statutory provisions like the comparative negligence statute.

The Doctrine of Stare Decisis

The legal principle that gives case law its binding force is called stare decisis — Latin for “to stand by things decided.” Under this doctrine, courts are expected to follow precedents established by higher courts within the same jurisdiction. A trial court in Erie County is bound by decisions of the Pennsylvania Superior Court and Supreme Court. The Superior Court is bound by Supreme Court decisions. This hierarchy creates consistency and predictability in the law, allowing attorneys to advise clients on likely outcomes based on how courts have decided similar cases in the past.

How Lawyers Use Case Law

When a Pennsylvania personal injury attorney argues a legal point — whether in a brief filed with the court, in oral argument, or in a mediation — they cite specific case decisions to support their position. A case citation such as Sehl v. Vista Linen Services, Inc. or Pyeritz v. Commonwealth refers to an actual judicial opinion that contains legal reasoning the attorney believes supports their argument. The opposing party cites different cases that support their position, and the court must evaluate which line of precedent applies and controls the outcome.

When Case Law Evolves

Case law is not static. Courts occasionally depart from prior precedent when they conclude that an earlier decision was incorrect, that circumstances have changed, or that the prior rule no longer serves the underlying purposes of the law. When the Pennsylvania Supreme Court overrules a prior decision, the new ruling becomes the controlling authority going forward. This evolution of case law reflects the common law’s capacity to adapt to changing social circumstances and emerging legal issues.

In practice, understanding the relevant case law in a personal injury matter is essential to evaluating the strength of a claim, predicting how a court is likely to rule on contested legal issues, and making informed decisions about settlement versus litigation.