"Illegal per se" means that an act is inherently illegal. “Per se” means “in itself or “by itself”. Thus, if an act is categorized as illegal per se, it means that it does not require any additional proof or surrounding circumstances, such as intent or a criminal mindset. Merely committing the act would make a person liable for the violation.

Illegal per se acts are common in criminal laws such as those involving intoxication. It is also common in connection with anti-trust and fraud laws, and also includes the concept of negligence per se.

What Is Needed to Establish a "Per Se" Violation?

In order for an act to be classified as per se illegal, it needs to be supported by:

  • Statute
  • Case law
  • The Constitution

Most illegal per se acts rely on statutes which define the illegal act. 

Usually it is only necessary to prove that the defendant violated the statute, and that the violation was the cause of the plaintiff’s injuries or losses. There is no need to prove that the defendant intended to commit the act. 

It is generally very difficult to raise a defense to an illegal per se violation. This is because a person can be held liable under per se laws even if they did not mean to commit the act. However, in very limited circumstances, it may be a defense if following the statute would prove to be more harmful than violating it, or if obeying it would be impossible.

What Are Some Examples of Acts That Are Illegal Per Se?

The most common form of illegal per se laws are those that cover drunk driving and blood alcohol content limits. Most states have a “zero tolerance” policy for underage drivers who drive while intoxicated. For example, under California DUI laws, it is illegal per se for drivers under the age of 21 to have any alcohol in their system while driving.  

Other examples of per se laws include:

  • Antitrust laws: There are several antitrust laws that make it illegal per se to engage in “unreasonable restraints on trade,” such as price fixing, group boycotting, and anti-competitive practices
  • Libel and slander: Certain statements can be classified as libel or slander per se. 
  • Negligence per se: This is a distinct category of negligence laws that usually involve actions that are grossly negligent and far beyond the normal standards of reasonable care

Do I Need a Lawyer?

Due to the complexity of laws and statutes, it can often be difficult to identify which acts are illegal per se. However, ignorance of the law does not constitute a defense to illegal per se violations. If you have been involved in an act that might be illegal per se, you should contact a criminal defense lawyer for counsel and advice. Alternatively, if you have been injured by a violation of per se laws, a personal injury attorney can help represent you in court and obtain recovery for your losses.