Can I sue from California, in small claim court, someone in England who is British?
I live in California and this guy sometimes comes to CA for business. He stole money from me in the U.S.
In California, the small claims court has jurisdiction over claims up to $10,000. In order to have personal jurisdiction over him:
He must have a summons and complaint hand delivered to him (or to certain other people such as an adult who lives in his household, or to his secretary if he has one). This is called "service of process" and there are professionals called "process servers" who can do this for you in most cities. The service of process can take place anywhere in the world and still be valid. The summons and complaint must be hand delivered by a person over the age of eighteen who is not a party to the lawsuit and is not your attorney.
The events that form the basis of the lawsuit must have happened in California, not merely the United States (long arm personal jurisdiction), or he must have the summons and complaint personally hand delivered to him in the State of California (tag jurisdiction).
If you win, either by default if he fails to respond by the deadline, or following a trial, you will get a piece of paper called a judgment that legally determines that he owes you $X, which you must then enforce. A judgment can be enforced, for example, by garnishing his bank accounts, garnishing monies due to him from an employer or from a sole proprietorship he operates, seizing tangible personal property that he owns with the assistance of a sheriff, or putting a lien on real estate he owns.
A judgment from a California small claims court can only be enforced against assets in California. There is a relatively simple process for having a judgment from California turned into a judgment from any other U.S. state. There is a relatively difficult and expensive process for having a judgment from California turned into a judgment from England that only sometimes works because some aspects of the U.S. civil court system (like punitive damages) are considered to be against public policy in England and are thus not enforceable there.
You cannot have someone arrested for failure to pay a civil judgment.
Enforcing the judgment is likely to be much more difficult than getting the judgment in your case.
It is also possible to make a criminal complaint if the acts genuinely constitute theft. If a prosecutor finds that there is probable cause to back up your claim, the prosecutor could obtain an arrest warrant from the court in the place where the theft took place and that could be served within California when the individual is present in California (i.e., he could be arrested in California, after which the criminal justice process would proceed).
Generally, to constitute theft, it must be intentional and must not be a mere breach of an agreement, in which case it is a breach of contract rather than theft.
Any theft small enough to be addressed in small claims court would probably not be considered serious enough for the government to request extradition from the U.K. for, a step usually reserved for serious felonies, but if extradiction was sought from the U.K., the process on the U.K. side is described here. Any extradiction request would be handled by the prosecutor's office and law enforcement, in cooperation with federal law enforcement agencies.