In England of the distant past, the word "doom" was a legal term, referring to a judgment imposing a punishment. Some etymological sources suggest it has common roots with the Sanskrit "dharma," a deeply complex word that can refer to customary social duties or divine law, depending upon the religious context.
When Buddhism was brought from India to Japan via China around 1,500 years ago, "dharma" was translated using the character 法 (hō), a word that now means "law," but which served as a religious term for much longer. Around the same time Buddhism was being introduced from the Asian mainland, so were Confucian models of law and governance set forth in ritsuryō (律令, the ancient Chinese code). The ritsu (律) were the rules of crime and punishment. Ryō (令, a character that is now usually pronounced "rei") were the rules of government, such as how courtiers had to dress while in mourning for a dead emperor.
The ritsuryō are long gone and today hō is the generic term for law, though it is typically used in combination with "ritsu to form hōritsu (法律, statutes), which is a generic term meaning "law," but one that also has a more specific meaning. It refers to the statutes passed by the kokkai (国会, the National Diet), which, under the Constitution, is the sole law-making organ of the state. In reality, however, a lot of laws are drafted not by Diet members but by bureaucrats who tend to delegate to themselves and their ministries the authority to fill in the details with regulations that don't go through the Diet.