Have you ever heard a Republican complain about "activist judges"? Or say that judges shouldn't "legislate from the bench"? They usually say things like that after the Court issues an opinion that allows women, African Americans, or members of the LGBT community to have rights and dignity and stuff. Republicans hate it when that happens. (Okay not all Republicans. But a lot of them.)
But what does it really mean when Republicans say that judges are "activists", and "legislating from the bench"? It means that the Court has interpreted the Constitution in a way that did not please the complaining Republican.
The Constitution is kinda like the Bible. People disagree about what different parts of it mean. And they fight about it. (Protestant Reformation, anyone?)
People who read the Bible literally are called fundamentalists. These are the folks who believe that God created the world in seven days, for example. There's a kind of constitutional interpretation that's sorta like that. It's called textualism.
If you're a fan of textualism, you believe that when the Supreme Court writes a decision, they can only talk about rights that are listed in so many words in the Constitution. That means that if a right is clearly listed in the words used to write the Constitution, then the Court can use those words to decide a case. If it's not listed, they can't use it.
For example, let's say the state of Michigan told soldiers to move into some dude's house without that dude's permission, when no war was going on. (Michigan would never really do this.) If the owner of the house wanted to evict the soldier, and lost in the lower courts, the Supreme Court could take his case and use the Third Amendment to say that the state law had to go. And that would allow the homeowner to kick out the soldier.
(Betcha never even heard of the Third Amendment. And now that you know that the Third Amendment says soldiers can't just move in to some random dude's house during a time of peace. Pretty crazy, right? Who says the Constitution can't be fun?)
The problem with textualism is that you're stuck with only the words that are actually part of the Constitution. So if you wanted an abortion, for example, an originalist would say you're out of luck, because the Constitution does not list the right to an abortion in so many words. (More on that later.)
Some people also ask what the dudes who wrote the Constitution meant when they wrote it. These people also want to look at what people living in 1789 would understand the words in the Constitution to mean. And they look at how they did stuff in 1789. (Scalia was a huge fan of using the original meaning of the Constitution. And his pal Justice Thomas still is.)
One example of this thinking is found in D.C. v. Heller, the only gun rights case to ever make it to the Supreme Court. In this case, the Court did some research, and found that people in 1789 would have understood the Second Amendment to allow people to keep handguns in their houses for personal protection.
Sometimes, textualism and original meaning are lumped together and called originalism. So if you're a fan of only using the actual words in the text of the Constitution, and only what they meant in 1789, you're an originalist.
Precedent is just a fancy way of saying, "Did we already make a decision about this? Can we just go with that?" And tradition just means, "How did we do this stuff before? Can we just keep doing it that way?" A person using this method doesn't necessarily look at how they did stuff in 1789. They just want to know how we did stuff before now.
Process Based Theory
This method looks at the Constitution and uses it to make sure that our democracy is working the way the Court thinks it should. This means that the Court uses this method to strike down laws that keep people from being able to vote, or being able to speak about politics.
This method uses the idea that the Constitution is a living, breathing document, and should reflect how we live today. So we should read the Constitution in a way that makes sense in our modern world. This is the method that was used to make the decision that gay people should have the right to marry in all 50 states.
Okay, I'm not gonne lie. This is my favorite method. I'm not the kind of person who thinks we should follow rules just because someone wrote some rules. I think we should look at those rules and ask if they serve us. If they don't, then we should come up with new rules.
And originalism never made any sense to me. I mean, who cares how they did things in 1789? George Washington did some great things, but he also had wooden teeth. And slavery was totally legal in 1789. Some rules about slavery were even included in the Constitution, in more than one place. Suck on that, originalists. Suck on that.
Just for fun, I thought I would summarize the different methods of Constitutional interpretation using that timeless truth, "Stuff happens."
Originalism: Does the Constitution list that stuff in so many words?
Original Meaning: How did they do that stuff in 1789?
Tradition/Precedent: How did we do this stuff before now?
Process Based Theory: Does this stuff help our democracy work?
Aspirational/Loose Construction: Let's use this stuff to help us live in our modern world.