How accountable would a person be for a crime committed when under alien influence?

Question

In my story, my MC ends up hosting a known (and common) alien life form within their head to keep it alive by joining with another sentient being; as a result, both host and alien life form's personality is infused while it's still inside her. This was done on dubious consent due to the death of the original host and the MC being the only compatible host and the alien can't live too long out of a host or stasis.

It is eventually removed but part of it is left behind and (unknowingly) grows into another generation of it's kind but it more parasitic and suppresses more of the host personality than the original alien. This caused the MC to commit a crime on impulse (eg; started a war by blowing up another ship as a preemptive strike). If the MC hadn't had the alien there, the likely chance of committing the crime would have been significantly lower and unlikely to have happened.

The new alien is found and removed fully and the MCs personality is restored to before the first alien was there. This opens them up for an appeal based on the alien's presence and how it affected their behavior, impulse and judgment.

My question is, how accountable would they be for the crimes they committed with the life form involved?

I did try to see which laws could apply but the sci-fi edge makes it hard to find specifics, especially on what sort of sentence they'd receive after too.

Answer 1

In order to be held accountable, all elements of the crime must be satisfied. As you've not defined the crime the character has been accused or convicted of, it's difficult to provide a precise answer, but the principle consideration is 'mens rea', or intent.

The law is quite clear that where a person lacks intent, they cannot be held liable, except for crimes of strict liability. Criminal law has a concept referred to automatism, which is an expression of this idea. A person who is sleepwalking or suffering from a night terror and kills someone cannot be held responsible for the act, since there's no accompanying intent. Similiarly, people have been acquitted on grounds that they were too inebriated or under the influence of drugs to have formed the requisite intent (although this is very rare and difficult to argue; however, the law still recognizes it). Therefore, a person under the influence of an alien could argue a similiar position.

However, there is the second element to consider as well, regarding her own contribution to the circumstances. But for the alien's presence, which she allowed, the event would not have occured. There have been cases in the past where people joined criminal organizations and were prohibited from arguing the defense of duress when forced to commit crimes on behalf of the organisation. This stems from a reasonable policy ground that individuals who willingly join criminal organisations cannot at a later date claim to have been forced to commit crimes under the threat of violence.

In my opinion, your character does not have to worry about this argument, because being a host to an alien is not actually illegal (I'm assuming); joining a criminal organisation is, on the other hand. Proceeding on the assumption that bonding with an alien is not illegal, in my opinion she has a perfectly valid ground to argue that she lacked criminal intent, and can therefore not be held responsible for what has occured.

Of course, this is assuming she had no agency whatsoever in commission of offence.

Answer 2

My gut instinct is, legally, while perhaps not identical, it would closely parallel an insanity plea.

I'm not a lawyer so I don't know the details of how this would play out, but in the United States there's a variety of criteria depending on the state.

One common element among states, emphasis mine, is:

In states that allow the insanity defense, defendants must prove to the court that they didn't understand what they were doing; failed to know right from wrong; acted on an uncontrollable impulse; or some variety of these factors.

The accused in your scenario seems like they could nicely make use of this type of defense. While they may not have a purely psychiatric condition, they could certainly argue that they still fit the criteria.

There's a number of guidelines and tests as well. From the page above (sorry not posting links to rule details, you can find more info on that page, but I'm typing on my phone and it's a pain):

Depending on the jurisdiction, courts use one or a combination of the following tests for legal insanity:

• The "M'Naghten Rule" - Defendant either did not understand what he or she did, or failed to distinguish right from wrong, because of a "disease of mind."
• The "Irresistible Impulse" Test - As a result of a mental disease, defendant was unable to control his impulses, which led to a criminal act.
• The "Durham Rule" - Regardless of clinical diagnosis, defendant's "mental defect" resulted in a criminal act.
• The "Model Penal Code" Test for Legal Insanity - Because of a diagnosed mental defect, defendant either failed to understand the criminality of his acts, or was unable to act within the confines of the law.

If your world's legal system uses some guidelines similar to one or more of the first three there, I could see a defense holding up.

The "Model Penal Code" test, though, may or may not apply.

You could research cases in the past where the insanity defense was used successfully as inspiration.

Answer 3

The answer cannot be black or white.

Several factors have to be taken into account, and it also depends on the legislation.

Factors to be taken into account:

• is the existence of the life form acknowledged by the mass? If in my real world I say that I stole a car because the purple jeejuice living in my garden told me, I would at most declared insane.
• is the influence of the life form established? In other words, was the host aware of the consequences of the hosting? Again in the real world one cannot claim that they didn't know that drinking a whole bottle of vodka would make them drunk.
• was the hosting voluntary or forced? Back to the vodka, if you are pointed a gun at your head to swallow the whole bottle down it might be seen differently than if you drank it out of your will.

And then the legislation: up to few years ago (if not even today, I am no expert in this) in many countries a man killing another man would be judged less severely if the homicide would happen to defend his honor, for example immediately after finding that the other man was having an affair with his wife. Or nowadays in some legislation being under influence when killing a person in car accident is an aggravating circumstance.

Wrapping up, it all depends on the law system you are setting up.

Answer 4

I would consider researching criminal charges where someone has a split personality.

• https://gould.usc.edu/why/students/orgs/ilj/assets/docs/10-2%20Saks_Article.pdf
• https://link.springer.com/article/10.1007/BF02238859

How does your community view alien/human mind-melds?

Is this like an illicit drug? Your MC should have known better, so is criminally responsible?

Is this like a mental illness? Your MC did not know better, and now receives treatment restoring them to a point of mental competence

Is this like a normal life event? Like getting bad news, emotionally tough, but not an excuse for illegal behavior? Sp MC had a responsibility to control their conduct?

Answer 5

Diminished responsibility is probably the mitigation that your MC will use: https://en.wikipedia.org/wiki/Diminished_responsibility

The MC will stand trial based on the criminal actions that were committed (blowing up the ship), they may attempt to convince a court that lesser charges apply (e.g. war crime->manslaughter), which the court may or may not accept. If found guilty of any charge, then mitigating/aggravating circumstances of alien possession will be considered in sentencing, which would likely have the effect of reducing the punishment, but there may be unavoidable legal minimums.

Further considerations:

• This type of possession seems common in your world, are there specific laws (e.g. possessed in charge of military equipment) that your character may be violating?
• A war has been started, this tends to be taken pretty seriously. It's almost impossible to conceive that there won't be an enormous amount of political interference in this trial. The result will set an enormous legal precedent, be appealed in the highest courts, drag on for years/decades and likely lead to the creation of new laws.
• The crime was also military, it's likely to be tried by a court-martial, which can have very different process and outcome.

On Mental health defences:

• Insanity defence: You MC was of sound mind, but not in control of their actions. A typical result of an insanity defence is being sectioned for mental health, which wouldn't apply here, making it unlikely a court would accept this defence.
• Being unfit to stand trial: MC is now 'cured', this would be pretty difficult to argue.

Answer 6

THIS IS OF COURSE NOT LEGAL ADVICE I AM NOT A LAWYER I AM JUST A GUY CONSIDERING THIS ON THE INTERNET

In my story, my MC ends up hosting a known (and common) alien life form within their head to keep it alive by joining with another sentient being; as a result, both host and alien life form's personality is infused while it's still inside her. This was done on dubious consent due to the death of the original host and the MC being the only compatible host and the alien can't live too long out of a host or stasis.

I think the same principle as duress would apply here IF the alien life form themselves was the perpetrator, at least in parallel. If you go and borrow money from someone, only for them to chase after you with a gun demanding their money back and your only reasonable way to get away was to steal someone's motorcycle, whether you could apply a duress defense depends on who that guy you borrowed money from is. If you had a reasonable belief that he was an upstanding guy, then you could apply the duress defense. If you knew he was an SOB, you couldn't claim duress because you should have known what you were getting yourself into.

It is eventually removed but part of it is left behind and (unknowingly) grows into another generation of it's kind but it more parasitic and suppresses more of the host personality than the original alien. This caused the MC to commit a crime on impulse (eg; started a war by blowing up another ship as a preemptive strike). If the MC hadn't had the alien there, the likely chance of committing the crime would have been significantly lower and unlikely to have happened.

This makes it more probable that a duress defense would succeed on paper. If this parasitic personality thing was not known to occur before the MC dealt with it, then her lawyer would be able to cogently argue something duress adjacent (as noted in several previous answers, it would be easy to say that the MC had no mens rea, and she couldn't bear responsibility for the situation if there was no reasonable way to foresee the consequences thereof).

However, as pointed out by @David258:

A war has been started, this tends to be taken pretty seriously. It's almost impossible to conceive that there won't be an enormous amount of political interference in this trial. The result will set an enormous legal precedent, be appealed in the highest courts, drag on for years/decades and likely lead to the creation of new laws.

For your story, this generates a lot of plot. Anyone who thinks your MC is a threat (like, say, your antagonist, or more insidiously, people whose aims are lined up with hers but who think she's a dangerous element for starting a war) or who have something against those aliens and want to create some kind of precedent to make hosting them illegal-- or else under some kind of controlled system-- will have ample reason to try to make the trial about crucifying the MC: the legal precedent would be worth way more than mere gold. Conversely, people who want to help your MC aren't just her friends: the aliens, for one, are going to be VERY invested in making sure any trial goes her way, and even people who may not like the MC personally may try to help her trial because they are incentivized to make sure that the alien hosting is legal.

Basically, because there are lots of cogent legal theories that the MC could cite in her defense, but pretty much all of them are active defenses, and because the actions of the MC are very politically significant, this is going to be a politically dictated trial more than a legally dictated trial unless your judge and jury are very, very impartial. This can be great for your story if you need to generate a major plot point. It can also be terrible for your story if it starts taking away from other major plot points.

Answer 7

I think, at least the way I understand the US legal system, they would be held accountable. If you look at cases of defenses for DID (formerly MPD Multiple Personality Disorder) claiming that an alternate state of consciousness (another "personality") committed a crime doesn't hold up in a court and the person still goes to jail. Especially if the fact remains that the entity in MC's head is still in there in any form at the time of the trail. If it's still in there, it's the responsibility of the body, not necessarily the "personality" in charge, except in cases where the person is deemed legally insane for not understanding right from wrong (which others have pointed out). So, I would suggest poking around Dissociative Identity Disorder as a legal defense, maybe there is a case where it was a successful defense I'm not aware of? Could lead you to some interesting places regardless.