The Costa Rican legal system is based on the French civil code. As in most places some petty crime is found in major cities and crowded tourist areas. Do not carry your passport, but rather a coy of the data page, or loads of cash around. Do not leave your things out of sight in public places, and generally display good judgement. There are several scams that try to trick unsuspecting foreigners with thieves working in pairs, where one distract and the other rob. Check information on these issues before going.