Although the term "Lawful" is thematically appropriate for alignment in D&D, it is also misleading. A lot of people gravitate heavily towards the root of the word ("law") and thus comprehend it by its simplest implication that lawful beings only function if they follow the rules. Any rules. That is neither accurate, nor is it normal.
A "lawful" being favors order, structure, and logic. Practicing routines, observing traditions, and performing ritual habits are some of the most basic examples of a lawful-minded individual. These individuals tend to be organized, thoughtful, and even meticulous in their daily routines.
Rules and laws, whether written or unwritten, exist for different reasons. They may be in place to protect the innocent (good) or benefit the privileged few or elite (evil), but they work with the expectation that everyone potentially affected subscribes to and abides by them. Otherwise, anarchy and chaos would threaten the structure and stability of whatever it is they seek to preserve.
The key to alignments is recognizing that there are degrees to each aspect. They point to the stronger tendency but that does not exclude the individual from choosing to act differently. Such acts aren't done by accident as long as they possess free will and have the capacity to contemplate their actions. A lawful person knows that they are bending the rules and finds reason to justify it.
A chaotic person, however, doesn't really care if the rule is broken or not because the rule itself has no value or meaning for them. It is someone else's construct that imposes limitations on them and others in an effort to exert control on forces outside themselves.
