Legal precedent is established until the laws change. The various legislatures/governing-bodies of the US can change the law whenever they please. When those laws then come into conflict with other laws out there, you have to have a ruling by a court. Sometimes this is intentional.
Which court does the ruling is super complex and sometimes they are not called courts, FYI. Judicial bodies, sometimes called courts, are also super complex. In general, the US legal system is more like the Ancien Régime than anything else, in that we strive to make sure no two people are governed under the same law. Just kidding, sorta. ;)
In the case of SCOTUS, they mostly rule on matters that affect the US constitution, and only if they feel doing so. They then make a ruling, and that becomes the new way the laws work. Sometimes this makes a law null-and-void, sometimes it just sets guidelines on how to make a law function. Again, super complex. There are many other courts in the US that can similarly do things at laws, but SCOTUS gets the most news.
TLDR and very over-simplified:
Legal precedent is established until the laws change. The various legislatures/governing-bodies of the US can change the law whenever they please. When those laws then come into conflict with other laws out there, you have to have a ruling by a court. Sometimes this is intentional.
Which court does the ruling is super complex and sometimes they are not called courts, FYI. Judicial bodies, sometimes called courts, are also super complex. In general, the US legal system is more like the Ancien Régime than anything else, in that we strive to make sure no two people are governed under the same law. Just kidding, sorta. ;)
In the case of SCOTUS, they mostly rule on matters that affect the US constitution, and only if they feel doing so. They then make a ruling, and that becomes the new way the laws work. Sometimes this makes a law null-and-void, sometimes it just sets guidelines on how to make a law function. Again, super complex. There are many other courts in the US that can similarly do things at laws, but SCOTUS gets the most news.