Supreme Court Chief Justice John Roberts warned that Americans may "take democracy for granted" in his annual year-end message published Tuesday.

"[W]e have come to take democracy for granted, and civic education has fallen by the wayside. In our age, when social media can instantly spread rumor and false information on a grand scale, the public’s need to understand our government, and the protections it provides, is ever more vital."

Why it matters: The statement about the power of online misinformation, coupled with Roberts' assertion of the federal judiciary's independence throughout the message, reads as a mission statement ahead of President Trump's Senate impeachment trial — over which the chief justice will preside.

"We should reflect on our duty to judge without fear or favor, deciding each matter with humility, integrity, and dispatch."

"As the New Year begins, and we turn to the tasks before us, we should each resolve to do our best to maintain the public’s trust that we are faithfully discharging our solemn obligation to equal justice under law.”

Flashback: Roberts and Trump disagreed about the independence of the federal judiciary back in 2018 after the president criticized judges who ruled against his administration, calling them "Obama judges."

That prompted Roberts to issue a rare public critique aimed at the president, saying the U.S. doesn't have "Obama judges or Trump judges, Bush judges or Clinton judges."

Go deeper: