Half Guilty

How would the American legal system punish conjoined twins if one committed a murder while the other was completely innocent?


Let’s consider, for the sake of argument, that we are dealing with dicephalic parapagus conjoined twins, conjoined twins with two heads sharing one body. Each twin controls one half of the body, neither can control the other’s half of the body, and neither can feel what the other feels. This is the physiology of the Hensel twins, Abigail and Brittany Hensel. Further, you must accept that these are two separate individuals because: 1) they have two separate consciousnesses, 2) they exhibit distinct personalities, or 3) they each had to pass the driving exam. They are entangled singletons – two consciousnesses in one continuum of skin whose individuality is defined partly by their conjoining (see bio-ethicist Alice Domurat Dreger).

When considering the punishment for one guilty conjoined twin, it is necessary to put aside all of the factual considerations that may arise when one conjoined twin commits a murder to the detriment of her innocent, connected sibling. Put aside the idea that the innocent twin had any control over the guilty twin’s hand. Put aside the idea that the court may impute the guilty action to the innocent twin, finding her an accomplice in the commission of this murder. Put aside the idea that the court could find that the innocent twin had some duty to stop the murder from occurring. To accept any of these ideas is to find the conjoined twins entirely innocent or entirely guilty and runs outside the scope of this problem. Accept, for the purposes of this problem, that the jury has found one twin guilty and the other is merely an innocent bystander — she did not participate in the act nor could they have stopped the homicide from occurring.

The question posed is not purely speculative. According to 18th century French historian Henri Sauval, a murder of the kind presented was perpetrated in the 17th century by Italian conjoined twins. Born in 1617 in Genoa, two boys were held together by the stomach. One twin was completely healthy while the other was mute, deaf, and blind. Sauval records that the healthy twin stabbed a man to death and was tried, convicted, and sentenced to death. However, the twin was not executed “on account of the innocence of one of its component halves.” It was impossible to put one to death without twin killing the other. Unfortunately, Sauval failed to mention whether they were subsequently incarcerated or released after the death sentence was commuted, leaving this scenario ripe for legal analysis in the abstract.

Findings of Guilt

Before dolling out punishment, there must be a finding of guilt. The Fifth Amendment of the Constitution provides “No person…shall be deprived of life, liberty, or property, without due process of law.” When we speak of due process, we speak of fundamental fairness: the prosecution must prove all of the elements of a crime beyond a reasonable doubt through a fair procedure before a fair finder of fact. Crimes deal with conduct which society deems anti-social and therefore deserving of punishment. The term conduct is used in a broad sense to cover the two distinct components of a crime: 1) the act and 2) the state of mind accompanying the act. Therefore, when the Legislature passes a law outlawing a particular crime it will include a definition of the act and the requisite mental state to commit the crime. A crime cannot be consummated without fulfilling both of the elements of act and intent.

Under federal law, murder is defined as follows: “Murder is the unlawful killing of a human being with malice aforethought.” 18 U.S.C. § 1111(a). Here, Congress has defined the act of murder as “the unlawful killing of a human being” while the state of mind to commit a murder is “malice aforethought.” Malice aforethought is one of those lofty legal concepts that exists mainly so scholars can debate its meaning. Essentially, malice aforethought is a deliberate intention to take away the life of a “fellow creature,” according to the California Penal Code. Cal. Penal Code § 188.

In order to convict someone of murder, the prosecution must prove beyond a reasonable doubt that the accused committed the proscribed act and harbored this requisite mental state. The paradox presented with this problem is that although we have two inextricable entwined people, only one twin can be convicted of the crime. As in most criminal prosecutions, the jury serves as the finder of fact and must make the determination of guilt. For the purposes of this argument, we must suppose that only one twin can be convicted of the crime. Otherwise there is no legal dilemma. Once there has been a finding of guilt, the court attempt to determine the punishment for this crime, being ever respectful of the innocence of one of the twins.


The broad purposes of the criminal law are to make people do what society regards as desirable and to prevent them from doing what society considers to be undesirable. To achieve this end, the State allocates punishment for bad acts as opposed to rewards for good acts, emphasizing the discouragement of undesirable rather than the encouragement of the desirable. There are several theories underlying punishment, each with specific ends and particular means. These theories include:

Deterrence — Deterring the criminal or society (by way of example) from committing crime by giving him an unpleasant experience such as jail time.

Incapacitation — Incapacitating the criminal by removing him from society to protect the populous from further criminal conduct.

Rehabilitation — Rehabilitating the criminal through appropriate treatment or training.

Retribution — Retribution, or justice, is imposed on criminals by society for the wrongs they have caused.

Proposed Punishments

1. Capital Punishment

The death penalty stands as the most impractical of all the potential punishment choices. As there is only one conclusively guilty actor in the pair, the court would have to find a way to kill only the guilty twin. In the novel The Siamese Twin Mystery by Ellery Queen (1933) the authors considered the practical angles of this problem, including how to electrocute one Siamese without damaging the other, and in the end resolved the problem by clearing the twins of the crime. Depending on the extent of the conjoining, which in this case is substantial, it is likely impossible to kill one without killing the other. While this punishment would protect society from further harm by either twin, the execution of an innocent person runs so afoul of due process and the morals of American society, capital punishment cannot be used in this case.

2. Life Without Parole

As an alternative to the death penalty, Courts hand down sentences of life without parole. This represents sufficient leniency by the court but still raises constitutional concerns of jailing an innocent person for the duration of her life. Again there is the problem of denying someone their liberty without convicting them of a crime. There lies an exception to this doctrine under the criminal law for criminal forfeitures. This is when the State seizes property used in the commission of a crime (houses, cars, boats) even though the true owner had no knowledge of its illicit use. Under this doctrine, the injured, innocent owner can seek remittance of the property from the State. This concept lends itself by analogy to a murder involving only one conjoined twins. The State would presumably be in its rights to seize the unlawfully used property (i.e. their shared body) but the innocent twin would be given the opportunity to remit forfeiture in their body as a “joint tenant in common.”

3. Separation

To consider more extreme approaches to punishing the guilty twin, the Court could order the twins separated so that the guilty twin may be punished. Even if this Solomonic option were possible in this case, as physiologically it appears impossible, this action raises grave Constitutional concerns. The Supreme Court has held that the body to be inviolate, providing slim exceptions to this rule as in the testing blood alcohol content, chemical castration, and the death penalty. This punishment smacks of the Sharia law practice of chopping off a convicted thief’s hand. Furthermore, it is hard to argue that separation would only punish one of the twins as each would be left immobile, one half of a complete body. Separation surgeries have some success as in the case of Jodie and Mary Attard (although this surgery was undertaken knowing full well that it would and did kill the weaker twin). Modern scholars estimate the rate of successful separation surgery at around 5% (see also the Bijani twins). With such dismal rates, sentencing conjoined twins to separation surgery would be the equivalent of a death sentence.

4. Suspended Sentence

If the Court finds that the Constitutional limits of due process are so great that neither twin may be punished, the Court may be obligated to let the twins go free. This would be the ultimate downward departure from sentencing guidelines. Exercising this option calls to attention the balancing of American morals: which do we hold higher, the punishment of an innocent life or freeing a guilty one? To allow a convicted murderer to go free spits in the face of retribution and that holy notion of justice. Furthermore, Justice Scalia might argue, this option yields the ultimate killing machine: a person who cannot be punished for murder because their physiology precludes punishment. In light of this concern remember that the circumstances of the murder are so unlikely that it has only occurred once in known history. However, say the conjoined twin did kill again, it is hard to imagine that a jury could bifurcate the finding of guilt across the twins for a second time.

5. Monetary Sanctions

Finally, monetary sanctions may satisfy the underlying problem presented. While it is hard to accept monetary sanctions in the place of traditional punishment, this option may be the only permissible alternative. Primitive and ancient societies relied on a form of tort damages, known as “wergild,” to compensate the families of murder victims and to control crime. The Germanic tribes had some success with this option until the Norman Conquest of the 9th century which did away with the practice. The problem with this punishment is that the average person would be reticent to assign a monetary value to surrender his life as he would get no utility from the money. Tort law, on the other hand, provides monetary compensation in wrongful death lawsuits, assigning millions for the loss of life. However, here we speak of the criminal law of murder, not the civil law of tortious liability. Monetary sanctions have never been popular in the modern era. Additionally, it is hard to argue that monetary sanctions would affect only one member of a conjoined twin pair.


As actors under American criminal law, conjoined twins present paradoxical obstacles to the application of traditional methods of criminal punishments. The Western notion of individuality precludes such duplicitous beings from orthodox measures to remedy criminal action, particularly the crime of murder. Constitutional limitations of due process and guarantees of life, liberty and property militate against equal treatment of these actors under the law. I believe that within our Constitutional framework, the only thing to be done in this situation is to release the conjoined twins. Even if the jury sentenced the conjoined twins to death, the court would have to commute the sentence and release the twins. The guarantees of due process under the Fifth and Fourteenth Amendments prohibit punishing an innocent actor. Furthermore stare decisis, the doctrine that states that courts must follow the precedent of preceding and higher courts, presents an additional danger. If the court decided to punish the innocent twin despite her innocence, there would be nothing to stop the State from punishing others who have not been convicted of committing crimes (see also enemy combatants, plea of not guilty by reason of insanity, etc.).

While this solution may seem like a grave injustice to society, consider the innocent parties injured through mistrial, the criminals released because of shortcomings of shoddy police work, and statutes of limitations preventing the delayed filing of charges despite ironclad certainty. Such is the nature of our legal system. With these limitations come the freedoms and guarantees of the Constitution, preventing an overreaching government from undue interference into the lives of private citizens and frivolous legal action.



Chained for Life (1951). A dramatization of the situation presented.

Those Extraordinary Twins by Mark Twain (ebook provide by Project Guttenberg).

Tom Waits Interviews Tom Waits. In this interview Tom Waits offers the story of a conjoined twin who committed a murder in 1890 in Baltimore. As far as I can tell, there is no merit to this story.

Hard cases make bad law.

27 thoughts on “Half Guilty

  1. Think prevention; the state has the power to institutionalize people to protect the public regardless of guilt in special circumstances. Think health quarantine or insanity. Also, people who are incarcerated frequently leave behind spouses or children whose lives are changed nearly as dramatically as that of a conjoined twin, also without special findings.

  2. You are missing the major failing point of this whole hypothetical argument. How could a conjoined twin murder someone without the other being somehow complicit? In most situations, one twin cannot even sleep when the other is awake. How then could a twin act independently enough to murder someone without the involvement of the other twin, especially if, as you say, each twin controls half the body. They cannot walk or perform any other menial physical activity without the cooperation of the other.

    Therefore there is NO WAY one twin could be innocent and another guilty. It would be more like a situation where two robbers rob a bank and during the course of the escape, one kills a bank employee. Under our law, both are held liable for the death. They may not get the exact same sentence, but both are liable.

    In your scenario, both twins would be liable and a sentence that took into account the involvement of the pair would be rendered to both (less extreme than the killer may have received, but more extreme than an accessory may have received).

    Some may argue that this would let the “guilty” twin off with a lighter sentence than a non-twin murderer. Perhaps, but the twin’s situation is also much different. The twin doesn’t have the mobility of an individual–and with the more extreme sentence served by the “less guilty” twin, that twin would be more apt to intervene in any future criminal activities attempted by the guilty twin. In effect, the guilty twin would have a 24/7 monitor of his/her activities.

    I don’t see the issue you are claiming here. You are trying to create a situation where to physically conjoined individuals can perform acts of which their other is completely unaware and has no control over. That simply is not possible.

  3. this happens. I saw it on ripleys believe it or not. but back in the 1400s or 1500s when it happened, they imprisoned one, but not the other. sort of like house arrest, where the one had control of one arm, and the other had control of the other arm, the guilty bad twin, had their arm bound, and they wore a gag with a hood over their head. the innocent twin was free to go on their merry way.

    I am sure there is a shot or something to paralyze the bad twin, or put them to sleep so the other can have some peace and quiet, but of course nowadays, it becomes cruel and unuaual punishment with all the lawyers, and such, I am surprised one twin doesnt charge the other with rape because they dont like the way the other goes to the bathroom, along the lines of “eeew they touched me down there” when the other was doing nothing other than going to the bathroom.

  4. The other twin would know about the murder taking place and, without reporting it to police or acting to stop, be complicit.

  5. In the abstract, if a death sentence were decided to be appropriate notwithstanding the twins issue, the option of surgery that would have greater chance of success at the cost of the survival of the guilty twin might be considered if the innocent twin found this acceptable.

    Outside of this, the US constitution and legal system are quite clear that “No person…shall be deprived of life, liberty, or property, without due process of law.”, being constitutionally guaranteed, takes precedence over EVEN the legal system itself. The founding fathers made it that way intentionally. This was so that the government belonged to the people, not the other way around. It is one of the many safeguards against tyranny. It has been judged in the inception of the United States of America that the government being allowed to even ONCE be allowed an act of tyranny against a SINGLE innocent citizen is a greater threat to life, liberty, and (what has been changed to) the American way than a hundred murderers escaping justice. The founding fathers were in no way ambiguous about this, and changing this caveat in the constitution is (theoretically) not alterable without a referendum, amongst other processes.

    As such, any loss of freedom would have to be managed by giving the innocent party ‘custody’ over what is done with the body during the designated period of incarceration. Suspension of the guilty party’s driver’s license is a start. This would be basically require the constant supervision of a dedicated officer of the law, but appears to be about the only means to satisfy constitutional requirements AND punish the guilty party.

    I would submit, however, if this were to happen once, it would be within the power of the court to give the innocent party responsibilities regarding ensuring the guilty party did not once again commit such actions.

    While the mechanism known as the justice system seems massive and well nigh invincible, it rests at the edge of a great many slippery slopes. The American forefathers put the balances they did in for very good reasons. Whether those checks and balances still function is another debate.

  6. One last thing. I do not claim to AGREE with the course of action in this specific circumstance, BUT … it is what the constitution demands of the courts. The courts can not make demands of the constitution, only interpret it. It’s how the system works.

  7. You guys are fighting the hypo. In any case, easy enough to come up with a viable scenario:

    The conjoined twins are hired to act. The part is that of a murderer. One twin is supposed to hold a knife to the neck of another actor, and then the director yells cut. Intent is that CGI blood will be added later. Instead, that twin uses the knife to slash the throat of the actor. Slashed actor dies. Second twin had no idea the first twin was going to do this, but first twin confesses that he had been planning to do this since they got the acting gig.

    Okay, now what?

  8. “One twin was completely healthy while the other was mute, deaf, and blind”

    Totally possible, Patrick and Benson.

  9. @Patrick If you remember, the situation DID happen in the 1600s. However, one of the twins was blind, mute, and deaf. It’s very likely that the other twin had much more power to do as he pleased since the other was living in a dark world, so to speak. So it is a valid point when one of the conjoined twins is weaker than the other in some way, which is usually the case. It’s rare that the two twins are perfectly equal in every way.

  10. Pardon my cynicism, but there are plenty of innocent people in prison and on death row. The American justice system (at least the laws enacted that drive it) is just a part of the prison-industrial complex. Prison-for-profit. We have the highest percentage of our population imprisoned in the world. That is insane. I have little doubt that the hypothetical person(s) in question would be locked up for life.

  11. The twins born in Genoa in 1617 were named Lazarus and Johannes Baptista Colloredo. Lazarus was a healthy man, while Johannes Baptista was a parasitic twin with essentially no consciousness of his own. They toured Europe as curiosities in the 17th century and Lazarus allegedly killed someone in a bar brawl. According to the book “The Two Headed Boy” by Jan Bondeson, he did not serve time for the murder.

    There is a more recent legal precedent involving conjoined twins. The film “Chained for Life” was partly inspired by a real-life incident involving Lucio and Simplicio Godino, pygopagus conjoined twins from the Philippines. While the brothers were visiting their home country in the 1920s, one struck a man with their car. The other brother was not involved in driving the car. They were indeed both exonerated because the judge could not justify imprisoning the innocent brother.

  12. To answer a comment above:

    You could indeed murder without the other knowing twin knowing. All it would require is poison. Poison could be acquired using messages, letters, etc. to a friend who would then say place the poison somewhere where the twin could easily grab it without the other knowing (see: under couch cushion) and then slip the poison to the individual.

    Great article.

  13. To Patrick who posted on December 31, 2009:

    Please broaden your mind, you are very ignorant. You are obviously either very young or just inexperienced. There certainly is many ways that a conjoined twin could commit a murder of which the other had no involvement. To give a crude example, a set of conjoined twins is sitting on a couch next to a person. Twin 1, always known to carry a utility knife on his belt decides he doesn’t like the person sitting on his side of the couch, takes out his utility knife and stabs him to death. This occurs in the matter of two seconds and the second twin has no chance to react.

    Of course this scenario assumes the twins are joined at the hip so as to allow them to sit down properly, which is a possible scenario.

    I’m not entirely sure what your idea of conjoined twins is, but it’s obviously incorrect.

    I agree with Kam that the only option is to allow the pair to go free so as not to have a miscarriage of justice in convicting an innocent person. Once case law and/or stare decisis has been established, there is nothing to stop the state from executing you as well as anyone it wishes for that murder.

    Even if a conviction were entered, it would be overturned by a superior court, 100 percent of the time if the second twin was innocent.

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