(CNN) He was never called upon to break a tie or influence how the Senate impeachment trial might end, but Chief Justice John Roberts' legacy will be forever entwined with President Donald Trump's.

It's not just that Roberts was in the chair presiding over the two-week hearing and historic vote on Wednesday to acquit Trump, just as Chief Justice Salmon Chase oversaw the acquittal of President Andrew Johnson in 1868 and Chief Justice William Rehnquist that of President Bill Clinton in 1999.

Roberts now faces unprecedented litigation at the Supreme Court involving the President's personal business dealings. The justices will hear three cases in March testing Trump's efforts to block subpoenas from the US House and a Manhattan district attorney for his tax returns and other financial records.

The disputes challenge the respective powers among the branches of government and could ultimately determine whether Trump makes his tax returns public, as his recent predecessors chose to do.

Other cases involving the President and top officials, such as former White House counsel Don McGahn , are wending their way through federal courts, as are multiple challenges to Trump administration policies.

If Trump wins another four-year term, Roberts could be in the position of ruling on a Trump-dominated docket until 2025.

Irrespective of whether this President serves one term or two, America's 17th chief justice is already bound for an unusual union with the 45th President, arising from the combination of Trump's impeachment trial, Supreme Court litigation and their dueling notions of an impartial federal judiciary.

When Roberts heard the first major challenge to a Trump administration policy, the travel ban directed at majority-Muslim countries, he wrote that Trump should be treated like any other US president.

The travel ban, Roberts wrote in a June 2018 opinion , "is an act that ... could have been taken by any other President." Roberts rejected evidence of Trump's anti-Muslim remarks, saying that "we must consider not only the statements of a particular President, but the authority of the Presidency itself."

Whether Roberts' time presiding over the impeachment trial has altered his view of Trump might be seen over time. Roberts is in his 15th year as chief justice and, at only age 65, he could easily serve five more years, or twice that.

At the impeachment trial

The Constitution specifically dictates that the chief justice presides over the impeachment trial of a president. The role is distinct from the real authority of the chief justice at the Supreme Court.

The Senate has the "sole power," according to the Constitution, to decide whether a president is convicted or acquitted. A two-thirds vote is required, and on Wednesday afternoon the Senate failed to reach that 67-vote threshold or even a simple majority. The vote was 48-52 to convict Trump on an abuse of power charge and 47-53 on an obstruction of Congress charge.

The US House in December had passed two articles of impeachment related to Trump's alleged conditioning of US security aid to Ukraine on Ukrainian investigations of Democrats. Last Friday the Senate voted against hearing from witnesses who might have direct knowledge of Trump's dealings on Ukraine.

After that vote, Senate Minority Leader Chuck Schumer, a New York Democrat, queried Roberts as to whether he would become involved in other matters . "Is the chief justice aware that in the impeachment trial of President Johnson, Chief Justice Chase, as presiding officer, cast tie-breaking votes on both March 31 and April 2, 1868?"

Appearing to speak from a prepared text, Roberts responded, "I am, Mr. Leader. The one concerned a motion to adjourn; the other concerned a motion to close deliberations. I do not regard those isolated episodes 150 years ago as sufficient to support a general authority to break ties."

Roberts continued, drawing a line between the legislative and judicial branches, "If the members of this body elected by the people and accountable to them divide equally on a motion, the normal rule is that the motion fails. I think it would be inappropriate for me, an unelected official from a different branch of government, to assert the power to change that result so that the motion would succeed."

As Roberts sidestepped the controversy over witnesses, he also showed little emotion as he read senators' often awkward, leading questions for the House impeachment managers and Trump's lawyers (per the customary process). Senate Majority Leader Mitch McConnell, a Kentucky Republican, said a total of 180 questions were delivered to Roberts to read.

One of the most dramatic moments came when Roberts rejected an attempt by Republican Sen. Rand Paul of Kentucky to induce him to say aloud the name of the alleged whistleblower who first brought Trump's Ukrainian dealings to public light.

Perhaps most striking was the many hours Roberts endured on the dais hearing piercing criticism of the President, who is becoming a regular litigant at the Supreme Court. US House managers characterized Trump as a liar and cheat, a man who put his own interests above those of the country.

Trump's lawyers rejected those assertions but seemed to accept some transgressions, saying that no matter what the President had done, his conduct did not warrant a Senate conviction.

In the courtroom

Neither Johnson nor Clinton faced voters for another term after their impeachments, and Chief Justices Chase and Rehnquist did not hear protracted court disputes in the vein of what Roberts already has on the docket related to Trump.

The cases tied most directly to Trump, centered on whether his personal business records are subject to subpoena, will be heard on March 31.

Unlike his role in the Senate, at the high court Roberts will cast votes and, in fact, could steer the outcomes of the cases, Trump v. Mazars, Trump v. Deutsche Bank and Trump v. Vance. Roberts not only sits at the center of the elevated mahogany bench but also resides at the ideological middle of the nine-member court.

Trump's veracity, which was attacked by the House managers during the impeachment trial, is also at issue in the subpoena cases. As lawyers for the House noted in one of their filings to the justices, "A common thread in each of these inquiries is the accuracy of statements made by President Trump on various financial disclosures."

House lawyers say the disclosures are needed for committees in the House of Representatives that are exploring the possibility of new legislation on conflicts of interest and other ethical concerns.

Trump's lawyers say the House lacks the constitutional or statutory authority to subpoena the documents, held by Trump's longtime accountants and banks: "To call these subpoenas unprecedented would be an understatement. This is the first time that Congress has subpoenaed private records of a sitting President."

They quarrel with the House's assertion that the Trump financial information is needed for a legislative purpose. Trump lawyers noted that a request to the Mazars USA accounting firm said the House wanted to investigate the accuracy of the President's financial statements to see if he had broken the law. Such an investigative focus, Trump's lawyers say, reveals that House committees are not engaged in a legislative effort.

In Trump v. Vance -- testing a subpoena sought by Manhattan District Attorney Cy Vance, who is looking into "hush money" paid to women who claimed affairs with Trump -- the President's lawyers have asserted that he is immune from criminal investigation -- not only from indictment, which had been common understanding -- while he holds office.

On how judges should rule

Beyond the Senate trial and Supreme Court litigation, Trump and Roberts have collided over regard for the impartiality of the judiciary. Trump has suggested in remarks on Twitter and elsewhere that he believes his judicial appointees would side with him, while Democratic appointees would automatically rule against him.

When Trump denigrated a California US district judge who had ruled against the administration as an "Obama judge," Roberts issued a statement in November 2018 that said, "We do not have Obama judges or Trump judges, Bush judges or Clinton judges. What we have is an extraordinary group of dedicated judges doing their level best to do equal right to those appearing before them."

In Roberts' most recent year-end report , issued on December 31, he might have had the Twitter-addicted President in mind when he said that "social media can instantly spread rumor and false information on a grand scale." The chief justice urged people to "celebrate our strong and independent judiciary."

At his State of the Union speech on Tuesday night, Trump shook hands with Roberts, as he did with other justices in attendance. Roberts looked somber, betraying none of what he was thinking, as was his way during the Senate trial.

As the Trump trial closed less than 24 hours later, Roberts expressed appreciation to Senate leaders for their support as he "attempted to carry out ill-defined responsibilities in an unfamiliar setting." He offered senators "good wishes as we carry out our common commitment to the Constitution."

And Roberts closed by saying he looked forward to seeing them again "under happier circumstances."