Sources of criminal law: penal codes, the Model Penal Code and the courts

The first class of Criminal Law for Law Enforcement starts with a question on the whiteboard: what makes something a crime? Professor Ray Desjardins, who spent 28 years with the Port Ardent police before he started teaching at Maumee Valley Community College, lets the room argue for a few minutes. Marco DiSanto says a crime is anything that hurts someone. Amara Okafor points out that cheating on a partner hurts people and is not a crime, while possessing a prohibited knife hurts no one and is. Priya Sandhu, who spent five years investigating bank fraud, says a crime is whatever the law says it is, and that the hard part is reading what the law actually says. Professor Desjardins circles her answer. This term, he says, the class will learn to read criminal law the way a good officer does: as a set of precise rules, each with elements that must be proved, which tell an officer when there are grounds to act and what evidence to gather. He introduces his co-instructor for the course, assistant county prosecutor Margaret Liu, who reviews police charges in Port Ardent every week and will tell them, often bluntly, which charges survive in court and why.

What criminal law is

Criminal law is the part of the law that defines conduct the state forbids and punishes. Three features separate it from other law. First, a crime is treated as a wrong against society as a whole, not just against the victim, so the case is brought by the state in the name of the people or the state, which is why Ohio cases are named State v. Smith and the victim is a witness rather than a party. Second, the consequences are the most serious the law imposes: a criminal record, fines, probation, imprisonment and the stigma of conviction. Third, because the stakes are so high, the accused is presumed innocent and the prosecution must prove every element of the offense beyond a reasonable doubt. In the United States, In re Winship (1970) held that due process requires proof beyond a reasonable doubt of every fact necessary to constitute the crime charged. Ohio law says a reasonable doubt is present when jurors, after carefully considering all the evidence, cannot say they are firmly convinced of the truth of the charge, and that proof beyond a reasonable doubt is proof of such character that an ordinary person would be willing to rely and act on it in the most important of his or her own affairs.

A civil case is different. If Amara's neighbor damages her fence, she can sue for the cost of repairs; she controls the case, needs to prove it only on a balance of probabilities, and the remedy is money. The same act may be both a civil wrong and a crime. If the neighbor broke the fence deliberately, the state may also prosecute for criminal mischief, and the two cases proceed separately with different standards of proof. Officers deal only with the criminal side, but they should understand the difference, because people often call the police about matters that are purely civil, such as a landlord keeping a damage deposit or a contractor who did poor work. Explaining that something is a civil dispute, and where the person can go for help, is part of the job.

Who makes criminal law

In the United States, the Constitution gives the federal government only enumerated powers, while the states keep a general police power to protect public health, safety and morals. As a result, most crime is defined by state law, and there are fifty different criminal codes plus the District of Columbia's. Congress can create crimes only in connection with its constitutional powers, such as regulating interstate commerce, taxation, the mail, immigration and federal property, which is why federal crimes appear in Title 18 of the United States Code and other titles. Cities and villages pass ordinances under powers granted by the state constitution and statutes; in Ohio, the constitution's home rule provision lets municipalities adopt their own police regulations as long as they do not conflict with general state laws.

The most important influence on American criminal codes is the Model Penal Code, a model statute written by the American Law Institute and published in 1962. It is not law anywhere by itself, but roughly two-thirds of the states rewrote their codes in the 1960s and 1970s using it as a template, and courts in other states cite it to interpret their own laws. Ohio's current criminal code took effect on January 1, 1974 and follows the Model Penal Code closely in its structure and its definitions of mental states. It is found in Title 29 of the Ohio Revised Code, with sections numbered by chapter: chapter 2903 covers homicide and assault, 2907 sex offenses, 2911 robbery and burglary, 2913 theft and fraud, 2923 conspiracy, attempt and weapons, and 2925 drugs. Ohio's legislature amends the code often; a version of the theft statute took effect as recently as October 6, 2026.

No crime without a law

A basic principle of criminal law is often stated in Latin as nullum crimen sine lege: there is no crime without a law. People can be punished only for conduct that was clearly defined as a crime before they did it. Ohio has abolished common law crimes by statute: no conduct constitutes a criminal offense in Ohio unless it is defined as one in the Revised Code. The US Constitution forbids ex post facto laws, so neither Congress nor a state may make an act a crime after it was done or increase the punishment for a crime already committed. For an officer, this principle means that the question is never whether conduct seems wrong but whether it fits a specific offense. A man who shouts insults at a referee may be rude, but unless his conduct meets the elements of a defined offense, there is nothing to charge.

The same principle requires laws to be clear. A law so vague that ordinary people cannot tell what it forbids, or that leaves police free to arrest whomever they dislike, violates the constitution. In Papachristou v. City of Jacksonville (1972), the Supreme Court struck down a vagrancy ordinance that made it a crime to be a rogue, a vagabond or a person wandering or strolling around from place to place without any lawful purpose, because it gave police unlimited discretion and failed to warn people what was forbidden. In City of Chicago v. Morales (1999), the Court struck down a gang loitering ordinance for similar reasons. Old vagrancy laws were once used to move along people whom police or the community considered undesirable, and their history is a reminder that clear limits on police power protect everyone.

The role of the courts

Legislatures write criminal law, but courts decide what the words mean. When a section is ambiguous, judges look at its words in context, its purpose and its history. Because criminal law can take away liberty, a real ambiguity that remains after these steps is resolved in favor of the accused. This is called the rule of lenity in American law, and Ohio codifies it: sections defining offenses or penalties are strictly construed against the state and liberally construed in favor of the accused. Courts also develop the general principles that apply to every offense, such as what counts as intent, when an accused caused a result and how defenses work. Many of these principles appear in no statute at all and are found only in case law.

Courts are bound by precedent, a principle known as stare decisis. A lower court must follow the decisions of the courts above it. In Ohio, municipal and common pleas courts follow their district court of appeals and the Supreme Court of Ohio, which is the final word on the meaning of Ohio law. On questions of the US Constitution, every court follows the Supreme Court of the United States. Federal courts interpret federal crimes, with the Sixth Circuit Court of Appeals above the federal district courts in Ohio. This is why Ms. Liu tells the class that a single appeal decision can change how every officer in the province or state must investigate a type of case, and why police services issue training bulletins when an important decision comes down.

Reading a statute like an investigator

Officers do not need to memorize the Revised Code, but they must be able to find and read the section that fits a situation. Statutes are written in a precise structure. An Ohio citation such as R.C. 2911.12(A)(2) means Revised Code section 2911.12, division (A), subdivision (2). Section 2911.12(A) lists four ways of committing burglary, each defined by the type of structure, whether a person is present or likely to be present and the purpose of the entry. The charge must state which division applies, because each has different elements and, in Ohio, a different degree of felony. Every word matters. Definitions sections tell the reader what terms mean, and the same word can have a narrower or broader meaning than in everyday speech.

The code below shows one way to break a citation into its parts, the first step in finding the right provision. Linh Tran, who hopes to become a crime analyst, likes the idea that statutes can be read as structured data. Records systems in police services do exactly this when they let officers select an offense by its section number.

# Breaking an Ohio Revised Code citation into its parts
import re
pattern = re.compile(r"R\.C\. (\d{4})\.(\d+)(?:\(([A-Z])\))?(?:\((\d+)\))?(?:\(([a-z])\))?")
labels = ["title", "chapter", "section", "division", "subdivision", "item"]
for citation in ["R.C. 2911.12(A)(2)", "R.C. 2903.13(A)", "R.C. 2913.02(B)(2)", "R.C. 2925.11", "R.C. 2917.11(A)(1)"]:
    m = pattern.fullmatch(citation)
    chapter, number, division, sub, item = m.groups()
    parts = [f"title {chapter[:2]}", f"chapter {chapter}", f"section {chapter}.{number}"]
    parts += [f"{label} {value}" for label, value in zip(labels[3:], (division, sub, item)) if value]
    print(f"{citation:20s} -> " + ", ".join(parts))

R.C. 2911.12(A)(2)   -> title 29, chapter 2911, section 2911.12, division A, subdivision 2
R.C. 2903.13(A)      -> title 29, chapter 2903, section 2903.13, division A
R.C. 2913.02(B)(2)   -> title 29, chapter 2913, section 2913.02, division B, subdivision 2
R.C. 2925.11         -> title 29, chapter 2925, section 2925.11
R.C. 2917.11(A)(1)   -> title 29, chapter 2917, section 2917.11, division A, subdivision 1

A citation tells you where to look, but the work starts when you read the provision itself. Ms. Liu gives the class a habit to practice all term: read the whole section, including any definitions it refers to; list its elements one per line; and then, for each element, write down what evidence would prove it. That list becomes the investigator's checklist, and lesson 3 will turn it into a formal tool.

From the street to the charge

Knowing the law matters at every step of police work. Before acting, an officer needs grounds to believe a specific offense has been committed. In Ohio, officers file a complaint for misdemeanors, often by issuing a citation, and the case is prosecuted in municipal or county court by the city law director or prosecutor. Felonies must be charged by a grand jury indictment or, if the accused waives it, a bill of information filed by the county prosecutor, and the case is tried in the court of common pleas. Prosecutors decide whether the evidence is strong enough and whether to charge a different offense from the one listed in the police report. Choosing the right offense and documenting the evidence for each element is what makes the difference between a case that proceeds and one that collapses.

Ms. Liu describes the most common problems she sees in police files. An officer charges a more serious offense than the evidence supports, perhaps because the victim was very upset, and the case is later reduced or withdrawn. An officer writes that a suspect intended something without recording the words and actions that showed intent. An officer charges the right offense but under the wrong subsection, so the charging document has to be amended. Or the report never addresses an element at all, such as the value of stolen property, which determines the level of the offense. Each of these can be avoided by reading the section and building the file around its elements, which is the core skill of this course.