A multi-species space faring society will have to tackle a far more complex legal system than we are used to on Earth. On Earth if you commit an act which is a crime in the country you are in, then you can be arrested.

In rarer circumstances if you commit an act which is not a crime in the country you are in, but is a crime in your home country, then upon returning home you can be charged with the crime. An example of this is that Canadian Citizens can be charged under the Child Sex Tourism law for under-age sex or creating child pornography even though the events did not take place within Canada's jurisdiction.

If you commit a crime in international waters you are subject to the laws of the country linked with the ship you are on. Every ship must sail under the flag of a single country with a genuine link to the vessel.

Typically a ship in international waters flying the flag of it's parent nation is protected from being boarded by foreign vessels except if the boarding vessel has reason to suspect the ship of piracy or slave trading.

The above rules are a simplification of international law but they cover the basics that we will be looking at.

At first it seems straightforward enough, let's change the countries to alien empires and international waters to deep space and we are done. But hang on. Human laws typically derive from the same sources. So while there are some major differences between countries, on the whole killing another human is regarded as a heinous crime.

What if we made contact with an alien species who regarded death as insignificant or at least justifiable (think Klingons). Any human entering Klingon territory would be effectively giving up all protection of their life. One could argue the same is true of Somalia on Earth, but this is true because Somalia is a lawless state not because it's laws allow humans to be killed. The logical upshot is that all trade would have to be carried out in deep space out-with Klingon jurisdiction. Because the Klingon ships would be flying the Klingon flag then the trade would have to happen on the Earth ship. So what if the Klingons have an equal problem conducting trade aboard an Earth ship? One answer would be trade ports where both parties are governed by strict laws designed to facilitate trading.

What if a species made contact with Earth and decided that all animals are sacred to them and need a bill of rights protecting us from willfully killing them? Currently this isn't an issue as most countries accept that it's okay to eat animals and no country has enough power (or reason) to enforce such a global ban. But an alien nation could be far more advanced than us and willing to go to war to prevent us from the barbaric practises that we have (their perspective - not mine - for the record, I love a good steak).

What if a species had a whole layer of slave labour. If a slave made it onto an Earth ship, by our own laws we would be legally obliged to protect it. What if the enslaved race was sentient but not as smart as Humans? At what point is it okay to enslave another creature? On Earth it's an easy distinction - You can't enslave humans, but you can make any other animal do what you want. Of course, when you have an animal working for you it is protected from harm and suffering - apart from death. You can't beat your dog, but you can take it out and kill it. What if it's an elephant - are they smart enough? At what level do we define another species as having the right not to be enslaved? What if a human being falls below that entrance criteria (because of brain damage), what protection do we afford them?

What if we encounter an entire planet full of primitive life. Can we do what we want with it, or is it protected and allowed to evolve?

With our analogy of deep space being international waters, we would have to agree upon how far an empire's jurisdiction extends. It makes sense to say that it covers the immediate area around their star(s) but not to extend into the vast distances between multiple star systems. If an empire (say the Romulans) settled planets around 27 stars. With the average distance between stars in our galaxy being something like 6 light years, this means that the empire would approximately cover an area of 1,728 cubic light years - a vast amount of space which could not be realistically patrolled or enforced. Therefore in Starship VL we are going to limit legal control of space to the immediate area around each star system. For the sake of argument we'll say 1/10th of a light year. This distance could be covered by a ship at Warp 9.5 in 35 minutes.

Another issue with our new legal system is penalties. In a moneyless society what viable penalties are there apart from community service and imprisonment. Community service doesn't seem particularly viable as in the future most menial tasks will have been automated (picking up litter, removing graffiti etc.). We certainly don't want to start imprisoning everyone for minor offences. So what is the penalty for a minor crime?