Free Will and Criminal Responsibility: What Courts Actually Need to Decide

Free will and criminal responsibility sound like a pair that must rise or fall together. If people do not choose freely, how can a court blame them? A 2026 opinion paper in Frontiers in Psychology argues that the pairing is looser than most people assume — and that free will and criminal responsibility have been tangled up by a confusion about what the word “will” even names (Schleim, Frontiers in Psychology).

Stephan Schleim, a philosopher and psychologist at the University of Groningen, published the paper on 17 July 2026. His claim is not that responsibility is an illusion. It is almost the opposite: criminal law, properly understood, never needed the metaphysical version of free will in the first place.

Free will and criminal responsibility do not stand or fall together

Schleim starts with a housekeeping point borrowed from Gilbert Ryle. “Volition” is an artificial concept, Ryle argued — not a word people use in ordinary life, where the real questions are whether someone acted voluntarily, intentionally, and whether they are responsible for what they did (Schleim, Frontiers in Psychology). Much of the familiar debate, Schleim notes, then circles a single test: could the person have decided and acted differently under exactly the same circumstances? He calls that test practically unproductive. Nobody ever faces exactly the same circumstances twice, brains included, and a truly random decision would not be a freer one anyway.

The standard map of positions still frames the argument. Hard determinists hold that the world is determined and free will is impossible; libertarians defend free will by denying determinism; compatibilists locate freedom in the right kind of determination — acting through your own desires, beliefs and conscious deliberation (Schleim, Frontiers in Psychology). Schleim’s objection to compatibilism is sharp: calling a decision free because it matches your preferences says nothing about where those preferences came from. Schopenhauer’s old line does the work here — you can do what you want, but you cannot want what you want.

This is not a new panic. Schleim traces an intensive 19th-century debate in German-speaking countries, including calls for a new criminal law, and quotes the scientist Carl Vogt writing that free will does not exist and with it no responsibility such as morality and the criminal justice system want to impose (Schleim, Frontiers in Psychology). The revolution in criminal law that some natural scientists predicted then has not arrived since. Schleim suggests that is because the law was asking different questions all along.

Does neuroscience disprove free will? What the Libet experiment actually shows

The experiments most often wheeled out against free will are Benjamin Libet’s. Volunteers reported when they became conscious of a decision to move, while researchers measured brain activity — the readiness potential — that began before that reported moment (Schleim, Frontiers in Psychology). Headlines tend to stop there: the brain decided before “you” did.

Schleim reads the record more carefully. Libet himself did not deny free will, and he repeatedly pointed out that the readiness potential marks the initiation of a movement, not its execution (Schleim, Frontiers in Psychology). An urge can arise and still be stopped — his example is feeling the desire to pour a glass of juice over someone’s sweater, and then not doing it. Later research confirmed that initiation does not necessarily lead to action. Something further has to happen between the urge and the act, and the experiments do not settle whether that further step is conscious or not.

That gap matters for law. A brain signal that starts a movement is not a verdict on who controlled it.

Criminal law insight and control responsibility: the questions courts ask instead

So what does a court actually need? Under German law, Schleim notes, anyone over 14 is criminally responsible unless a pathological impairment undermines their insight or control — can the person tell right from wrong, and act on that insight? United States law works through a different structure, requiring a causal link between the criminal act and the criminal mind, with specific excuses such as duress or a qualifying mental disorder able to exculpate (Schleim, Frontiers in Psychology).

Neither system asks a judge to rule on determinism. Judges and forensic experts assess whether a legally defined excuse applies, and — here is the detail that does the heavy lifting — even a clear finding such as a brain tumour does not settle the case. The expert still has to assess how far the condition impaired perception, thinking, decision-making and conscious control in that defendant, because not every person with a brain tumour, even in regions linked to social cognition, commits crimes (Schleim, Frontiers in Psychology). Schleim calls the common confusion of causation with responsibility the “psycholegal error”, a term from the legal scholar Stephen Morse: an act can be caused without that fact alone deciding whether it is attributable to the person or to a disorder that overran their insight and control.

Everyday moral life works the same way, on his account. When someone spills a drink on you, your first questions are about intent and responsibility — accident, carelessness, malice — not about the physics of their neurons.

Analysis: the paper’s useful provocation is deflationary. It does not rescue a soul-like will, and it does not hand neuroscience a veto over blame. It says the courtroom’s working concepts — insight, control, excuse — were already built for a world of caused actions, which is lucky, because that is the only world on offer. The honest argument left is narrower and harder: which impairments genuinely take control away, and how would we know? That is a forensic question, answerable case by case. It will never produce a headline as clean as “free will is dead”. It might produce fairer verdicts.

Photo: Joe Gratz, via Wikimedia Commons (CC0)

Sources

1. https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2026.1811791/pdf
2. https://www.withrealityinmind.com/determinism-meaning/
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC11157510/