Contrary to popular movie belief, being a henchman doesn't just mean getting a red shirt and disappearing when the main villain takes the fall. Being a real henchman is completely unglamorous, the pay is rubbish and if the main perpetrator gets caught, everyone else who contributed to the crime may also find themselves liable up to and equal to the main villain. This article is going to look at what might happy to those unfortunate henchmen who get hauled off to jail by the heroes.
Like many of these articles, this is all based on English Law. US and other international legal systems may vary greatly, but this can hopefully just provide some ideas.
So, you have your criminal mastermind and his dastardly plot to take over the world through crime. He's going to need people to help him. In legal terms, the type of contribution varies, and hence the amount of possible liability. English law is old and hence there are a few quaint terms still kicking about to describe the different types of contribution.
The actual name for henchman liability is 'Inchoate Liability'. This literally means 'partial offences' but generally refers to the liability of others, secondary to the main offender. The main types of inchoate offences are Incitement, Conspiracy, Attempt and Participation. And all of these can easily appear in any modern day RPG campaign, both as offences committed by player characters and non-player characters alike.
Incitement is the act of persuading or encouraging another person to commit a crime, and a person can be found guilty and held liable of incitement, even if the actual offence was never committed.
Conspiracy is where there is an agreement by two of more persons to do an unlawful act or deed. Again, the full offence doesn't need to be committed for any conspirators to be found guilty. Of course, sitting round a gaming table or at a bar and discussing hypothetical methods of robbing the National Treasury do not count. As well as the act of conspiring there must also be an intention to actually do the deed. The moment when a hypothetical plan becomes a real one is up to the jury to decide.
Attempt is fairly self-explanatory. It's the offence you get charged with if the plan goes all wrong and the crime is unsuccessful. Whether this was due to the intended target being absent, the getaway car getting impounded, the bank being closed on Sundays or a bust-up by Police/SWAT/Superheroes is irrelevant. It's the actual attempt that counts, and attempt is defined as 'doing an act which is more than merely preparatory to the commission of the offence'. Again this is ultimately up to the jury. But generally, sitting in your house and ironing your wooly bandana is not considered to be an attempt to rob a bank, even if you wanted it nice and clean for the bank robbery. However, entering the bank whilst wearing the bandana may well be.
Participation is the main henchman offence. This is the liability of others who somehow help with the crime, and is also known as Accessorial Liability. In English Law there are three main types: Aiding and abetting, counselling and procuring. And I bet all three have been used in any modern day RPG and beyond.
Aiding and Abetting is as it sounds – literally helping out with the crime. All those black-masked mooks who assist with the bank robbery are aiding and abetting. So is the getaway driver who just sits outside, and so on. The key here is that all members of the 'team' have to have both the intention to commit the offence and knowledge of the essential matters of the 'plan'.
Counselling is an odd one, and refers to giving advice and instruction to the would-be crooks without actually taking part. Again there has to be intention and knowledge of what is going on.
Procuring is providing any equipment that is to be used in the offence, and like the others, there must be intention and knowledge of the requisitioner's purpose.
So, looking at our criminal mastermind now. If his bank robbery plan goes all wrong, he may find his henchmen being booked for Attempt and Aiding and Abetting, his weapons officer done for Procurement, and he himself liable for Conspiracy, Incitement and Counselling.
Still... international crime and world domination still pays off right? As long as you can get away with it, anyway!
Next time: The Medieval Home Show: Feudalism and Property Law of the Middle Ages.

