Sexual assault cases usually turn on the question of consent. That question often comes down to whether the accused honestly and reasonably believed there was consent at the time of the incident. The law calls this Mistake of Fact.
Few defenses are as misunderstood or as powerful as mistake of fact. Used carelessly, it’ll get you sent to prison. Used correctly, it can set you free.
A mistake of fact defense applies when the accused held a genuine belief, based on what they saw, heard, or reasonably understood, that the other person consented. The belief must be both honest and reasonable.
It is not enough to simply say “I thought she consented.” The belief must make sense under the circumstances as they actually appeared. That standard protects good-faith misunderstandings while still holding people accountable for ignoring clear signs of non-consent. Once the defense puts this defense into play, the prosecution must prove beyond a reasonable doubt that the belief did not exist or was unreasonable.
In plain English, if you had a reason to believe there was consent, that’s a valid defense, even if the complaining witness didn’t actually give consent.
When Mistake of Fact Might Apply
These examples show how an honest and reasonable belief in consent can arise.
Social Setting and Clear Communication:
A woman has been drinking lightly but is (or doesn’t appear to be) drunk. She is alert, coordinated, and interacting with others. Witnesses see her laughing, touching the accused’s arm, and she sends flirtatious messages to him from the same table. She later admits she asked to go to his room and started kissing him. She removed her own bra. When the accused took off the rest of her clothes, she never said no or resisted. She claims she never wanted intercourse and just laid there and showed no signs of enjoyment. She left right after the encounter and didn’t answer his texts the next day.
A panel could find that he reasonably believed she consented. Her words and actions supported that belief at the time, even if she changed her mind or regretted it and convinced herself it hadn’t been consensual.
Romantic Precedent:
Two people who have been together before end up in a similar situation as prior encounters. There is nothing new or alarming in the setting, body language, foreplay, or tone. He had to talk her into it, not for the first time, but once they got underway things seemed as they had been before. Afterward, she says, “You know I didn’t want that.”
The defense can show that the accused reasonably relied on the same cues that had always meant consent in the past.
Buzzed but Not Incapacitated:
Both parties have been drinking, but not to excess. The complainant’s speech is normal, she can stand and walk without help, and she joins in conversation with others. She later reports feeling “tipsy” or “lightheaded,” but not sick or confused. Witnesses say she appeared aware of her surroundings.
In this situation, the question is not whether alcohol was present, but whether it impaired her capacity to make and communicate a decision. A reasonable person could believe she had the ability to consent if she appeared coherent, responsive, and in control at the time.
Modern Perception and Strategy:
In the post–#MeToo era, military training has blurred the line between intoxication and incapacity. Many members of the command and potential panel members have been told, directly or indirectly, that sex and alcohol cannot coexist. The result is a “one drop equals no consent” bias that effectively removes a mistake of fact defense. Defense counsel must identify and challenge this issue during voir dire. In some cases, that cultural bias may be a strong reason to elect a judge-alone trial. A military judge is less influenced by command messaging or optics and is focused only on the legal standard: whether the alleged victim had the capacity to consent at the time.
When Mistake of Fact Does Not Apply
The defense fails when the belief is dishonest, careless, or based on ignoring clear signs of trouble.
Obvious Incapacitation
If the complainant is slurring, falling over, or unresponsive, any belief in consent is not reasonable. Even a minimally careful person would recognize incapacity.
Clear Refusal
If she says “no,” pulls away, or shows fear or resistance, the reasonableness of misinterpretation vanishes. Continuing after a clear refusal is never reasonable, unless, arguably, the other person reinstates (even in that instance we would advise taking a rain check).
Selective Memory
If text messages or witness statements show she resisted or cried, the claim “I thought she was just emotional but still wanted it” becomes a post-event rationalization, not a mistake.
Heavy Intoxication and Assumptions
If both parties were drunk and the accused cannot recall what was said or done, that is not a reasonable belief in consent. It is a lack of attention. The law will not recalibrate for the accused’s intoxication, only the accuser’s.
The Blackout Problem
A blackout is one of the most misunderstood parts of alcohol-related sex cases. It is a period of memory failure, not unconsciousness. A person in a blackout can appear completely functional, walking, talking, making decisions, and even initiating sexual activity, but later have no memory of it.
When someone reports being blacked out, that does not mean they were incapable of consenting (in a legal sense) at the time. It means their brain failed to store or record the memory.
If the accused saw someone acting alert, speaking clearly, and engaging willingly, it may have been reasonable to believe consent existed, even if that person later cannot recall the encounter. The law measures reasonableness by what could be observed, not by what was later “remembered.”
This is why blackout cases often hinge on what witnesses saw, videos captured, and timelines. The goal is to show that the accused’s understanding of the moment was based on visible reality, not hindsight.
If you see a report noting that your accuser claimed to be “blacked out,” don’t panic. That might be your way out.
The “Yes + Puke = No” Scenario
Two soldiers are out with a group. They drink heavily, flirt, and become physical. She is intoxicated but not incapacitated. More than buzzed, but she can walk, speak clearly, and pay her own tab. They return to her place and begin sexual activity. She becomes dizzy, sits up, leans over the side of the bed, and vomits onto her clothes. After she regains her bearings, she says she’s fine, and they continue.
Hungover the next day, she reports the encounter and claims that she was too intoxicated to consent. At trial, the defense raises the mistake of fact defense. The prosecution produces the vomit-encrusted pants as evidence, preserved for months in a sealed bag.
The odds of acquittal under these facts are not zero, but they are low. Vomit prior to sexual activity, or during, and the accused’s awareness of it, is likely to be interpreted as a sign of incapacity, regardless of the other conditions.
Continuing after that moment will be considered indefensible. Takeaway: Puke isn’t ballast. This is not an opportunity to get back to it and press on. It’s a cue to stop, get her a drink of water, and leave. (And check-in like a gentleman the next day.) That’s what a reasonable person would do.
“But I was drunk too!” is Not a Defense
Mistake of fact only works if the belief in consent was both honest and reasonable. The “reasonable” part is measured against the standard of a sober, prudent adult, not an intoxicated one. Your own drinking cannot be used to lower the bar for what counts as reasonable.
If you were drunk, and your intoxication caused you to misread the situation, that does not make your belief in consent reasonable under the law. The judge will tell the panel that voluntary intoxication cannot turn an unreasonable mistake into a reasonable one.
This rule often surprises defendants. In many cases, both parties were drinking, and it can feel inconsistent that only one person’s intoxication is treated as evidence of impaired judgment. It does make one wonder why, if neither person was capable of consent, both aren’t viewed as victims. Once in a while, a clever service member tries to get ahead of the issue by self-reporting to law enforcement. Not to claim victim status, but to preempt an accusation. It’s a foolish move. Command and investigators will treat it as a confession.
The Law is “a Ass, A Idiot”: Make Breakfast Next Time
First Scenario: A man and woman go on a date. They get along well but don’t spend the night together. On their second date, they do. They have sex, fall asleep, and at dawn he decides to wake her up with oral sex. The act is one of giving, not taking, true, but she was asleep, and therefore incapable of consent. Legally, it can qualify as a sexual assault.
Second Scenario: A married couple of ten years has a birthday tradition: one partner wakes the other up with oral sex. Both have done it for years without complaint or surprise. Even here, the law draws no exception. The person being touched is unconscious and therefore unable to consent in that moment. The right to withdraw consent exists at every stage, regardless of history or routine.
Third Scenario: The same couple, now strained and distant. They have not been intimate for weeks. Her birthday comes, and he decides that the old custom might serve as a peace offering. He acts with optimism, not malice. The problem is the same: she was asleep, and in this context, her claim that she would not have consented might carry more weight.
Would a military court convict under any of these scenarios? Possibly, and under a strict reading of Article 120, they would be justified. But this is a rare case where the lack of consent is a legal fiction, applied to 99% of cases, that is being exploited by an unscrupulous accuser.
Many judges and panels understand that intent and context matter. They may find the conduct technically meets the elements, yet choose to “nullify” out of common sense and fairness, viewing it as misguided affection rather than assault.
That unpredictability is precisely why mistake of fact as to consent exists, and why these cases turn on the attorney’s ability to frame reasonableness through the facts, the relationships, and the accused’s genuine perception at the time.
Mistake of Fact as to Age
A related form of this defense applies in cases involving alleged sexual activity with someone under sixteen. It is called Mistake of Fact as to Age. The rule is simple: if the accused honestly and reasonably believed the other person was old enough to consent, that belief can be a defense.
The belief must have actually existed and must have been reasonable under the circumstances.
When the Belief May Be Reasonable
You meet someone in a bar that checks IDs. She talks about having been there before and looks like an adult. She speaks and behaves like someone in her twenties. Nothing she says or does suggests she is underage. In this situation, it might be reasonable to believe she was of legal age.
When the “Belief” Fails
During conversation, she mentions homework, says her parents will be mad if she is not home by ten, and adds she just got her license. Those are clear signs she is under eighteen. Any continued belief that she was of age would no longer be reasonable.
The test is always the same: what did the accused actually know, and what would a reasonable person have concluded at the time?
Mistake of Fact in a Nutshell
1. What is “Mistake of Fact” in a military sexual-assault case?
A: It’s a defense based on what the accused honestly and reasonably believed at the time. If you believed, based on what you saw, heard, or understood, that the other person consented, and that belief was both genuine and reasonable, the law recognizes it as a defense. The government must prove beyond a reasonable doubt that no such belief existed or that it was unreasonable.
2. What makes a “reasonable” belief in consent?
A: It’s about what a careful, sober person would have believed in the moment. The question is whether the accused had good reason to think consent existed, based on what could be seen, heard, or understood at the time. That belief is more important than whether there actually was consent.
3. Does mistake of fact still apply if both people were drinking?
A: Possibly, but with limits. The belief in consent must be reasonable as judged by the standard of a sober adult, not an intoxicated one. Your own drinking cannot make an unreasonable belief seem reasonable.
4. Can mistake of fact apply when the “victim” was blacked out?
A: Yes. A blackout means an absence of memory, not unconsciousness. Someone in a blackout might appear awake, talk clearly, and act normally but later remember nothing. If a person appeared capable of consenting at the time, it can still be reasonable to believe consent existed.
5. What if the “victim” vomited during or right before sex?
A: Continuing after that point is almost always seen as unreasonable. The law expects a reasonable person to stop and care for the other person, not continue sexual activity.
6. Does mistake of fact apply between spouses or long-term partners?
A: It can, but it’s not a given. Even in a long marriage or relationship, consent must exist at each moment. Waking someone up with sex, even something that’s been part of the couple’s routine, can technically qualify as assault if the person was asleep and unable to consent at that time.
7. Can a military court convict someone in those “sleep” scenarios?
A: Yes, though many judges and panels use common sense and fairness when deciding whether a technical violation amounts to a crime.
8. What about cases involving someone underage?
A: That’s called “mistake of fact as to age.” It applies if the accused honestly and reasonably believed the other person was old enough to consent. For example, meeting someone in a bar that checks IDs and hearing her talk about past visits can support a reasonable belief. But if she mentions curfew and just getting her license, that belief stops being reasonable.
9. What happens if both people were too drunk to consent?
A: The law doesn’t treat them equally. The accused can’t use intoxication as a shield. Reasonableness is measured against a standard pegged to sobriety. Even if both were impaired, only one side is viewed as responsible for ensuring consent existed.
10. Why does the mistake of fact defense exist at all?
A: Because the law recognizes that misunderstandings happen in real life, especially in social settings involving alcohol, mixed signals, and prior relationships. It protects against criminalizing genuine confusion or misreading, but not carelessness or willful blindness.
Military sexual-assault law is built on the idea of consent and perception: what each person knew, saw, and believed in that moment, seen in hindsight through the lens of reasonableness.
Mistake of fact does not excuse carelessness or reckless behavior, but it protects against criminalizing misunderstandings that were honest and reasonable.
The defense gives the panel and judge a legal path to acknowledge human complexity without confusing regret with rape.
Free Article 120 Case Evaluation
If you’re accused of sexual assault, don’t guess what the rules are. We’ve defended these cases for more than twenty years. We know what evidence matters, what doesn’t, and how to fight when it looks hopeless. Call 800-319-3134 for a free, private talk with one of our lawyers.