What is “trapped in amber”? An originalist explanation

Anyone watching the Supreme Court this past term may have remarked on the frequency with which the justices talk about fossilized tree resin. Consider:The court in Trump v. Cook: “We see no reason, however, why our central bank ought to be ‘trapped in amber’ any more than any other aspect of our constitutional scheme.”The court in Watson v. Republican National Committee: “Statutes do not ‘tra[p] in amber’ every contemporary practice on the same subject matter.”Justice Sonia Sotomayor in Cisco Systems v. Doe I: “There also is no indication that Congress intended to ‘tra[p]’ the [Alien Tort Statute] ‘in amber.’”Justice Ketanji Brown Jackson in Wolford v. Lopez: “Such a narrow search results in a ‘law trapped in amber.’”Justice Elena Kagan in Trump v. Slaughter: “When, exactly is our law ‘trapped in amber,’ and when is it not?”Justice Brett Kavanaugh in Trump v. Barbara: “This Court’s constitutional precedents do not treat the 1791 or 1868 exceptions as a closed set ‘trapped in amber.’”Justice Amy Coney Barrett at oral argument in United States v. Hemani: “I agree with you that you don’t need to have just alcohol because that’s all there was at the founding and that would be trapped in amber.”The expression has become increasingly popular in the lower courts, too. Earlier this week, law professor Richard Re traced the history of the metaphor and its rapid spread over the past two years.As Re correctly recognizes, though early uses of the phrase evoked a living Constitution – one