Here's what 'pettifogging' means and why Chief Justice John Roberts would say it in the impeachment trial

Roberts had just listened to the impeachment managers and Trump's legal team sharply criticize each other early Wednesday morning after House Judiciary Chairman Jerry Nadler, a New York Democrat, made the case for issuing a subpoena for former national security adviser John Bolton's testimony.

Roberts said that kind of exchange was not appropriate and, providing a historical example, reminded the legal teams they they need to be on their best behavior.

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"In the 1905 Swain trial, a senator objected when one of the managers used the word 'pettifogging' and the presiding officer said the word ought not to have been used," Roberts said. "I don't think we need to aspire to that high of a standard, but I do think those addressing the Senate should remember where they are."

Merriam-Webster defines pettifogging as "worrying too much about details that are minor or not important."

In other words, Roberts said that if the senator in 1905 who accused his opponent of focusing too much on the petty details was behaving objectionably, today's impeachment teams that are throwing accusations of cover-ups and dishonesty against one another are also outside the bounds of proper behavior.

"I think it is appropriate for me to admonish both the House managers and the President's counsel in equal terms to remember that they are addressing the world's greatest deliberative body," Roberts said. "One reason it has earned that title is because its members avoid speaking in a manner and using language that is not conducive to civil discourse."

In his role as chief justice, Roberts presides over the trial -- his constitutional duty -- in a role that is highly public but unlikely to see him cast any votes. He has recited procedural rules, kept the clock and read aloud vote tallies.

Heading into the Senate trial, Roberts presides over the trial -- his constitutional duty -- in a role that is highly public but unlikely to see him cast any votes, because Republicans, who hold a majority of seats in the chamber, can overrule the chief justice's decisions.

The chief justice has long been known for his extensive preparation and an ability to foresee what's ahead that some colleagues have likened to three-dimensional chess.