Section 1.2: Primary vs. Secondary Sources

Fundamentals of Procedural Law by Adam J. McKee

As you delve into the world of law, one of the first and most vital distinctions you’ll encounter is the difference between primary and secondary sources of law. Understanding this distinction is a fundamental step in your journey, a little like learning your left foot from your right before you start to dance. Let’s dig a little deeper.

Distinguishing Primary from Secondary Sources of Law

Primary sources of law are the ‘original’ laws, the ones created by legislative bodies or judges. Secondary sources, on the other hand, are interpretations, discussions, or analyses of these primary laws. They’re like commentaries or guides that help us understand the primary laws better.

In the U.S., owing to our common law heritage (a system of law that relies on court decisions as a major source of law), judges’ written opinions in appellate (higher-level) court cases are considered primary sources of law. Another primary source of law is the statutes (laws) passed by legislative bodies like Congress.

Interplay Between Court Cases and Statutes

At first glance, court cases and statutes might seem quite distinct. They come from different institutions and are formed using different methods. But, in the intricate dance of law, they’re interconnected in ways that might surprise you.

Let’s think about this: some areas of law are shaped mainly by case law (laws formed by court decisions). For example, the law of criminal procedure (the rules for conducting criminal justice activities-what this book is about!) is primarily shaped by court decisions.

On the other hand, some areas are largely determined by statutes. Take substantive criminal law, which deals with what actions are crimes and what their punishments are. This is primarily governed by laws passed by legislative bodies.

In reality, most areas of law are an admixture of both case law and statutory law. They’re influenced by both, creating a complex interplay that shapes our legal system.

The Role of Congress and Administrative Agencies

Now, you might be wondering: how does Congress fit into this picture? Well, according to the Constitution, Congress has the power to make laws. However, when it comes to highly technical matters, Congress often delegates these powers to administrative agencies of the federal government.

These agencies have specialized knowledge to regulate these technical areas. So, they make regulations, which are rules or orders issued by these agencies based on the powers given to them by Congress. Because these regulations have the force of law (they can be enforced just like laws), they’re also considered primary sources of law.

Interestingly, many of these agencies have something called ‘quasi-judicial powers.’ This means they can hear cases involving violations of the rules they set. They function a bit like courts, even though they’re not part of the judiciary.

Decoding the Dance of Law

This complex interaction between different sources of law can be confusing at first but don’t be disheartened. Remember, just like learning a new dance, understanding the interplay of law takes time and practice. As you get more familiar with how different sources influence each other, you’ll start to see the rhythm in this intricate dance.

Remember that both primary and secondary sources of law have their place. Primary sources give you the original laws, while secondary sources help you understand and interpret them. And the dance between them shapes the fascinating world of law that we know today!


In law, understanding the difference between primary and secondary sources is crucial. Primary sources include original laws, namely statutes passed by legislative bodies like Congress, and judges’ written opinions in appellate court cases.

Secondary sources are interpretations or analyses of these primary laws. Despite appearing distinct, court cases and statutes interact in complex ways, both shaping the legal landscape. For example, while the law of criminal procedure is mainly formed by court decisions (case law), substantive criminal law is generally governed by statutes.

Furthermore, in technical areas, Congress often delegates law-making power to federal administrative agencies, whose regulations are also primary sources of law. These agencies may even possess quasi-judicial powers to hear rule violation cases. Therefore, legal studies involve navigating this intricate interplay between different law sources.

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Modification History

File Created:  08/04/2018

Last Modified:  06/29/2023

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This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

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