SPRINGFIELD — Legislators looking to impeach then-Gov. Rod Blagojevich largely had one word on their minds more than seven years ago: “cause.”

That’s the constitutional threshold they needed to satisfy in order to undo his election and remove him from office.

But despite only having to “determine the existence of cause for impeachment,” as it states in Article IV, Section 14 of the Illinois Constitution, lawmakers and their staffs at the Capitol had myriad other challenges.

The process was mostly unprecedented. Blagojevich was mostly unpredictable. And staff attorneys had only days to cobble together rules and evidence.

Now, those trials and tribulations have gotten a fresh look by Bernard Sieracki, a longtime Statehouse lobbyist and a professor at both the University of Illinois at Chicago and the Illinois Institute of Technology.

Sieracki, along with House Minority Leader James B. Durkin of Western Springs and Democratic state Sen. Andy Manar, of Bunker Hill, reflected on Sieracki’s new book, “A Just Cause: The Impeachment and Removal of Governor Rod Blagojevich” as well as their own memories of the ordeal late last month at the Abraham Lincoln Presidential Library and Museum.

The book, which came out in January, focuses on Blagojevich’s ouster from a legislative point of view.

The relatively opaque impeachment provision dealing with “cause” is where the title of the book came from, Sieracki told the panel. And despite empowering lawmakers to take up their “most consequential action” ever, as he wrote in the book, it had never been a major topic for those who drafted the 1970 constitution.

“They didn’t want to get involved with impeachment,” Sieracki said. “They just wanted to leave that up to the legislature and make that a political thing.”

Amid dispute after dispute with Blagojevich, Democratic House Speaker Michael J. Madigan and his legal staff had been researching rules and building a case for impeachment well before the governor was arrested by federal agents in December 2008. Among the corruption-related criminal charges was a plot to sell the U.S. Senate seat of President-elect Barack Obama.

But since he hadn’t been indicted when legislators began the impeachment process, they relied heavily on administrative misdeeds that had already been made public — including instances in which his administration flouted federal law on importing vaccines and ignored legislative rules on how much to expand health care.

Procedurally, the Illinois House is tasked with voting whether to impeach and the state Senate votes to remove from office.

Only twice had the legislature ever invoked impeachment proceedings, once for Supreme Court justice Theophilus Smith in 1833 and again in 1997 for justice James D. Heiple. The former was impeached but not voted out of office. Heiple was not impeached but left office when his term ended.

A House committee essentially acts as a grand jury, gathering facts and then voting on a bill of charges to send to the Senate for a trial, which included his alleged criminal activity as well as the administrative malfeasance.

Durkin, the ranking Republican on the House committee back then, told the audience last week it was important to go above and beyond what the constitution required for impeachment.

“We’re not required to find probable cause. We’re not required to provide due process or any process. We just have to find cause,” Durkin told the audience of approximately 200 at the Lincoln museum, adding they thought it was important to give the governor the ability to, say, subpoena and call witnesses to testify in his favor.

“We’re a country that is built on some process. If we’re going to reverse a popular election, let’s give this man his day in court. And he chose not to (participate),” Durkin said.

The House ultimately voted for impeachment, and on the last day of his trial in the Senate, Blagojevich showed up to address the members of the body.

Manar, then a staff member for the Senate Democrats, was tasked with escorting the governor to the Senate chamber from his second-floor office at the Statehouse. Sieracki recounts in vivid detail how, just before Blagojevich stepped onto the chamber floor, he grabbed Manar’s forearm and said, “Andy, I didn’t do anything wrong.”

Pointing to himself, Manar responded, “Governor, you don’t have to convince me. You have to convince those 59 people out there.”

Manar told the audience that on the final day of the proceedings, then-Chief Justice Thomas Fitzgerald, who presided over the trial in the Senate, “was about done. He was ready for this thing to be over.”

Fitzgerald wasn’t convinced Blagojevich was going to show up, Manar said, but he told Manar and other staffers to get him there expeditiously if he did.

“That’s what was weighing on my mind. I was convinced that if he walked into that corridor four seconds too late that Fitzgerald was going to say, ‘No thanks. Get out of here,” Manar recalled.

Blagojevich gave an impassioned speech, but a mostly political one that did not succeed in convincing any of the senators he shouldn’t be kicked out of office. The votes to simultaneously kick him out of office and prohibit him from holding office in the future, taken exactly seven years ago Friday, was unanimous.