Amy Coney Barrett makes her mark

• And Barrett is just as conservative as everyone knew she would be. She joined the court's rulings overturning Roe v. Wade, expanding gun rights and curtailing the powers of the federal government.
• But she is beginning to separate herself from the pack in important ways.

She seems less willing than some of her colleagues to fast-forward through parts of the legal process just to reach a particular outcome.

• She has explicitly criticized some of the ways other conservatives use historical analysis to solve modern questions.
• And in the term that just ended, her positions were significantly less favorable to former President Trump than those of any other Republican appointee.

Trump cases

Barrett joined the liberal justices in dissent when the court narrowed one of the charges the Justice Department has used in Jan. 6 cases, including Trump's. The majority did "textual backflips" to get around what should have been an "open and shut" win for the government, she said.

Every justice agreed that Trump should have been allowed to stay on the ballot in Colorado, but Barrett made a point to write that the conservative majority should have gotten there on narrower grounds than it did.

And her concurring opinion in the court's presidential immunity case had some flavors of dissent.

• Although she agreed with the basic proposition that former presidents must have some immunity from prosecution for their official acts, she again argued for a more nuanced way of applying that immunity — one that would allow more issues to go to trial.
• And she disagreed with a section of the ruling that bars courts from considering a president's official acts as evidence in the trials that are able to go forward.

Historical analysis

History has become an essential part of conservatives' approach to major cases, particularly when dealing with the Second Amendment. But Barrett has said repeatedly that some of her colleagues — most notably Justice Clarence Thomas — are being too doctrinaire.

• "Tradition is not an end in itself—and I fear that the Court uses it that way here," Barrett wrote earlier this year in a case about trademark law.

Particularly when resolving constitutional questions, she has said, history needs to be understood in context, not as the beginning and end of legal analysis.

• "Evidence of 'tradition' unmoored from original meaning is not binding law," she wrote in a Second Amendment case this year. "Historical regulations reveal a principle, not a mold."

Why it matters: Thomas' brand of historical analysis, pioneered by the late Justice Antonin Scalia, has become a bedrock on the right, often to the annoyance of actual historians.

• If Barrett can build support for a more flexible method, the court's basic approach to any number of big constitutional questions could begin to shift.

What we're watching

Every justice has their own idiosyncrasies, but only a small number can build majorities around them in any given case. Fewer still are able to turn their unique judicial philosophies into a lasting, widely used legal doctrine.

• She may not become one of them, but there's a roadmap for how she could.

Barrett's willingness to write her own concurring and dissenting opinions will help.

• Some of her colleagues don't do that very often, choosing to simply sign onto either the majority or the dissent without articulating their own thinking.

She is the youngest conservative on the court. She will still be there after Thomas and Justice Samuel Alito are gone and new, more junior justices cycle in.

• They're both adherents to a strict method of historical analysis, and they're both usually inclined to move quickly and rule broadly.

And it helps to be aligned with the chief justice, which Barrett often is.