An independent government agency established to safeguard Americans’ privacy and civil liberties will examine the FBI’s use of a powerful surveillance law that has become a lightning rod for President Trump and his supporters.

The Privacy and Civil Liberties Oversight Board on Tuesday voted to hold a public forum about revelations from the Justice Department inspector general. Earlier this year, the IG found errors in every FBI application to a secret surveillance court examined as part of an ongoing review of the Foreign Intelligence Surveillance Act.

The law was used to obtain a wiretap on a former Trump campaign adviser and has been a frequent target of Trump and his supporters, who say the Obama administration employed it to illegally spy on Trump’s campaign.

The five-member oversight board, which usually approves its inquiries unanimously, split along party lines, with the three Republican members voting to examine the implications of the IG’s findings. The board will also seek documents from the FBI and the Justice Department, according to a copy of the proposal members voted on that was reviewed by The Washington Post.

Democrats opposed looking into the IG’s work, with one board member arguing that the board risked its reputation for bipartisanship by wading into a partisan brawl.

“There is simply no need for us to pile on to the FISA . . . investigations that coordinate agencies are already doing,” Travis LeBlanc, one of the two Democratic members and a former senior official at the Federal Communications Commission, wrote in a seven-page memorandum.

The inspector general, Michael Horowitz, as well as congressional committees and the court that approves FISA warrants, are already reviewing the process. LeBlanc warned fellow board members that the issue “has grown increasingly charged and partisan over the past five months. Taken together, these factors risk creating a disturbing appearance of partisanship” in the board’s decision, he said.

The IG found no evidence to support Trump’s claim that the FBI illegally spied on him. But he has documented pervasive shortcomings and problems that suggest a systemic problem in how the FBI obtains warrant to surveil people in the United States, including American citizens and legal residents.

Late last year, Horowitz found that the FBI’s applications for a wiretap on Carter Page,the former Trump campaign adviser, contained “significant inaccuracies and omissions” and that agents “failed to meet the basic obligation” to ensure the applications were “scrupulously accurate.”

Horowitz selected a sample of 29 other applications to review and found problems with all of them. Some lacked documents, known as Woods files, that the FBI includes to ensure the accuracy of its applications to the court.

When the IG compared the applications to the corresponding files, he “identified apparent errors or inadequately supported facts” in 25 cases, and in the remaining four could find no Woods files at all.

The findings stunned defenders of the FISA process, who had long argued that, while secretive, it was assiduously managed so that applications were thoroughly reviewed and supported before they were presented to the court.

Adam I. Klein, the chairman of the privacy board, said that the issues Horowitz surfaced were precisely those that the board was established to examine.

“This is at the heartland of our jurisdiction,” said Klein, a lawyer and prominent researcher of FISA and other national security laws. “The IG found systemic compliance problems. At a minimum, we have a duty to inform ourselves.”

Klein described the board’s work as “an information-gathering exercise, at this point.”

The board was established in the wake of the Sept. 11, 2001, terrorist attacks, to provide an independent check on government surveillance authorities, particularly in response to new laws and executive orders that gave investigators intrusive powers to monitor Americans’ communications.

At times, the board has been essentially moribund and without staff, and critics have said it had been stripped of much of its independence. But it has been praised for its contributions on how to improve privacy protections in surveillance laws.

In addition to holding a public forum that Klein said would include “an ideologically diverse group of experts,” the board intends to request information from the inspector general, as well as the FBI’s general counsel and the national security division at the Justice Department.

Klein said the board plans only to examine counterterrorism matters, which would preclude any review of wiretap applications for Page or any investigation by the FBI of the Trump campaign.

The board will also request the number of investigations touching on prominent individuals in which the FBI sought an order from the surveillance court between 2015 and 2019. Those investigations, which the bureau defines as sensitive investigative matters, may include public officials or candidates for office, according to Justice Department guidelines.

LeBlanc argued there were better ways for the board to use its limited investigative resources and time that were also germane to its mission, including state and local police use of devices, known as stingrays, to track cellphones.

“We have no shortage of critical nonpartisan privacy and civil liberties concerns that warrant our attention — from the use of Stingrays to offensive hacking, intelligence information sharing practices, and the disproportionate impact of surveillance on people of color and religious minorities, to name just a few,” LeBlanc told The Post.

Klein said that the board was obliged to investigate potential misuse of the surveillance law, even if it meant wading into a fraught political controversy in the heat of a presidential election.

“We should never get into an issue for political purposes, but we should also not ignore very important issues for political reasons,” Klein said.