Concurrence in criminal law is the requirement that the guilty act and the guilty mind exist at the same time, with the mental state driving the physical act. A prosecutor cannot stitch together a crime from bad intentions on one day and a harmful act on another if the two were unrelated. The intent has to be present during the conduct, and in most cases it has to be the reason for the conduct. That timing rule is one of the oldest safeguards in criminal law, and it is also one of the most useful tools a defense attorney has.
The Two Ingredients That Have to Line Up
Almost every crime has two elements: a voluntary physical act (or a failure to act where the law imposed a duty) and a mental state. Concurrence is the rule that connects them. The act alone is not a crime. The thought alone is not a crime. The two have to meet.
A quick example makes the point. Suppose you decided last week to steal your neighbor’s bike, then changed your mind. Today you walk out and ride off on it, honestly believing it is yours. No theft. The intent existed at one time, the act existed at another, and they never overlapped. Now change the facts: you see the bike, decide right then to take it, and pedal away. Intent and act exist together. That is concurrence, and that is theft.
The mental state the prosecution must prove depends on the offense. The Model Penal Code sorts culpable states into four levels — purposely, knowingly, recklessly, and negligently — in descending order of blameworthiness.1Open Casebook. Model Penal Code 2.02 – General Requirements of Culpability Whichever one the statute requires is the one that has to be present during the act. A reckless driving charge needs the driver to be consciously disregarding the risk while behind the wheel, not weeks earlier.
The act itself has to be voluntary. The Model Penal Code excludes reflexes, convulsions, movements during sleep or unconsciousness, conduct under hypnosis, and any bodily movement that isn’t a product of the person’s effort or conscious choice.2University of Pennsylvania Law School. Model Penal Code If someone has a seizure and strikes a bystander, there is no voluntary act for a mental state to attach to, and concurrence never gets off the ground.
Temporal Concurrence
Temporal concurrence is the straightforward version: the guilty mind and the guilty act exist at the same moment. You decide to punch someone and you punch them five seconds later. The intent is present during the conduct. Most ordinary criminal cases satisfy this test without anyone pausing to analyze it.
Motivational Concurrence
Motivational concurrence asks something more demanding: did the intent actually cause the act? Overlap in time is not always enough.
The classic hypothetical: you plan to kill your uncle to inherit his estate. Driving to his house that evening, you accidentally run over a pedestrian who turns out to be your uncle. The intent to kill him and the act of killing him existed at the same time. But the intent did not motivate the act. You ran him over by accident, not because of your plan. Most courts would find concurrence lacking because the mental state did not drive the physical conduct.
This is where defense work gets real. Even if a prosecutor can place a guilty thought and a guilty act in the same window, that may not be enough. The prosecution often needs to show the thought was the reason for the act.
When Intent Forms Mid-Act
Concurrence has an important exception for ongoing conduct. If an act begins innocently and the guilty mind forms while the act is still happening, courts treat the whole duration as one event. The intent only has to show up at some point before the act ends.
The leading authority is Fagan v. Metropolitan Police Commissioner, a 1969 English decision that still appears in American criminal law courses. A driver accidentally rolled his car onto a police officer’s foot. When the officer told him to move, the driver refused, cursed at the officer, and turned off the ignition. The initial act of driving onto the foot was unintentional. But parking on someone’s foot was a continuing act. The moment the driver decided to leave the car there, a guilty mind attached to an ongoing physical act, and concurrence was satisfied.
The continuing act doctrine matters because criminal conduct rarely begins with a clean, deliberate first move. Someone may start doing something accidental and then, mid-act, make a choice that turns the conduct criminal. Without the doctrine, obvious guilt would slip through on a technicality.
Transferred Intent
Transferred intent fills a different gap. If you swing at one person, miss, and hit someone else, your intent to harm transfers to the actual victim. Without the doctrine, a defendant could argue there was no concurrence as to the person actually struck, because the intent was aimed elsewhere. Courts close that argument by treating the original intent as sufficient for the crime against the unintended victim.
Crimes Where Concurrence Doesn’t Apply
Some offenses do not require a mental state at all. These are strict liability crimes, and because there is only one element to prove, concurrence has nothing to coordinate.3Library of Congress. Mens Rea: An Overview of State-of-Mind Requirements for Federal Criminal Law Selling alcohol to a minor is a common example, even when the seller genuinely believed the buyer was of age. Many traffic offenses work the same way, and statutory rape is a strict liability crime in many jurisdictions. The defendant’s intent, knowledge, or honest mistake is irrelevant. If the charge is a strict liability offense, concurrence arguments will not help.
Using Concurrence in a Defense
For anyone facing charges, concurrence is more than a classroom concept. If a defense attorney can show that the required mental state existed at a different time than the physical act, the prosecution has a hole in its case. The argument surfaces most often where the timeline is disputed or where the defendant’s state of mind shifted during a sequence of events.
The motivational side of the doctrine does similar work. Even when a prosecutor can put the guilty mind and the guilty act in the same moment, the defense can argue the intent did not actually drive the conduct. Winning that argument can be the difference between a conviction on the charged offense and an acquittal or a reduction to a lesser charge that fits whatever mental state the defendant actually had.