Confusion about the Branches of American Government

I wonder if my American friends can help clarify something for me.

As an Australian, what I see of your government in the media confuses me. I know you have 3 branches; Legislative, Executive and Judicial.

The way I understand it, the Legislative branch, which is Congress, makes the laws.

Why then, is the Supreme Court, which is meant to be enforcing laws, always in the news for making this, that and the other a law?

For instance, gay marriage wasn’t legal until the Supreme Court decided it was. And the supreme court is deciding whether or not to extend the eviction moratorium.

Why is the Supreme Court deciding what’s law and what isn’t instead of Congress?

It doesn’t make sense to me.

In the American system of government, the legislative branch writes laws; the judicial branch interprets laws; and the executive branch enforces laws. While it is not explicitly enshrined in the US Constitution, there is an extraordinarily long history of judicial review here - the courts have the authority to ensure laws and treaties pass legal and constitutional muster and declare them invalid if they don’t.

The Supreme Court is the final arbiter of what a law means and whether it is Constitutionally valid. With regard to ending the eviction moratorium, the Supreme Court ruled the executive branch has no authority to unanimously enact such a moratorium and that Congress would need to pass a law establishing one. In the case of gay marriage, the Supreme Court ruled (in United States v. Windsor) that the Defense of Marriage Act, outlawing recognition of same-sex marriage, was in violation of the Due Process Clause of the Fifth Amendment; then (in Hollingsworth v. Perry) that California could resume recognizing same-sex marriage at the state level; and finally (in Obergefell v. Hodges) that state-level bans on same-sex marriage are unconstitutional, as violations of the Due Process Clause and Equal Protection clause.

edit: would just like to add that gay sex acts were illegal in my state when I was growing up and in my early adulthood. my city’s newspaper carried weekly photos of men arrested for engaging in or soliciting gay sex. there’s still a sign in a park that was a popular place for meetups warning that plainclothed and uniformed officers frequently patrol the park and anyone observing suspicious behavior should call 911.

To put it a bit more simply (but not as in-depth), Congress makes laws, but the President can veto them unless they pass by 2/3 or more. Laws cannot be enforced if they’re not consistent with the Constitution, however, and the final say on if a law is constitutional is the Supreme Court.

Additionally, it can also interpret how the Constitution applies to certain things. Like for example saying that the Constitution, as written, would apply to ensuring gay marriage is recognized.

So the Supreme Court essentially strikes down laws, but it doesn’t create them. It can’t make something out of nothing like Congress can, but it can codify an interpretation of the existing Constitution that wasn’t being used before.