The judicial branch is the one branch that does not actually make legal rules. We know that job is granted to the legislative branch (from the Constitution), and the legislative branch often hands over that power to the executive branch (that's how agencies make rules/regulations). If the judicial branch isn't where the laws that bind us are created, why do we spend so much time reading judicial decisions?
The judicial branch resolves disputes. It JUDGES different scenarios brought by people in disagreement and makes decisions on whose interpretation of the law is correct. Because we have so many sources of legal rules (legislative branch, executive branch, and even state governments), they are bound to conflict. The judicial branch sees disputes between two people (or entities), each arguing that their interpretation of the laws is correct. Each side supports its case by referencing the various levels of legal authority (Constitutional being the highest), trying to convince the judge, using analytical reasoning, that the law intends to lead to the conclusion it hopes for.
For this reason, the judicial branch exhibits some interesting and controversial legal questions - the intersection of various laws or rules and unique arguments about why one supports a particular real-world situation. The decisions of courts are lasting. They are binding for the future (as binding precedent). However, judges do not make laws, even though judicial precedent acts as law. Judges simply interpret various scenarios and tell us which version of the law (law as already constituted), is right.
Because judicial precedent tracks changes of legal interpretation, it's an interesting place to see how our country's laws have "evolved" over time. Subscript will be publishing reports on how various legal subjects have evolved over time, by viewing the Supreme Court's decisions in those areas.