WASHINGTON (Reuters) -- A federal judge in Washington on Wednesday ordered that Democratic presidential candidate Hillary Clinton may have to testify in a lawsuit related to the private email server she used while secretary of state.
U.S. District Judge Emmet Sullivan said the parties in the case, the State Department and conservative watchdog group Judicial Watch, also struck an agreement about the scope of the testimonies that some of Clinton's former top aides will give in the case.
Those testimonies, known as discovery, will take place over the next eight weeks and may yield information that would require Clinton herself to be deposed, Sullivan said in an order.
Clinton on the campaign trail:
Hillary Clinton's 2016 campaign
US judge says Clinton may have to testify in email lawsuit
BALTIMORE, MD - APRIL 10: Democratic presidential candidate Hillary Clinton holds a campaign rally at City Garage April 10, 2016 in Baltimore, Maryland. Voters will head to polling places for Maryland's presidential primary April 26. (Photo by Chip Somodevilla/Getty Images)
Democratic U.S. presidential candidate Hillary Clinton laughs as she listens to Representative Steve Israel (D-NY) speak on a gun control panel in Port Washington, New York April 11, 2016. REUTERS/Lucas Jackson
NEW YORK, NY - APRIL 09: Democratic presidential candidate Hillary Clinton holds a Latino organizing event on April 9, 2016 while campaigning in the Brooklyn Borough of New York City. The New York Democratic primary is scheduled for April 19th. (Photo by Andrew Renneisen/Getty Images)
SPRINGFIELD, MA - FEBRUARY 29: Democratic presidential candidate former Secretary of State Hillary Clinton speaks during a 'Get Out The Vote' rally at the Lyman & Merrie Wood Museum of Springfield History on February 29, 2016 in Springfield, Massachusetts. Hillary Clinton is campaigning in Massachusetts and Virginia ahead of Super Tuesday. (Photo by Justin Sullivan/Getty Images)
BOSTON, MA - Former Secretary of State Hillary Clinton speaks to supporters at the Old South Meeting Hall during a rally in Boston, Massachusetts on Monday February 29, 2016. (Photo by Melina Mara/The Washington Post via Getty Images)
MINNEAPOLIS, MN - MARCH 01: Democratic presidential candidate former Secretary of State Hillary Clinton greets patrons at Mapps Coffee on March 1, 2016 in Minneapolis, Minnesota. Hillary Clinton is campaigning in Minnesota as Super Tuesday voting takes place in 12 states. (Photo by Justin Sullivan/Getty Images)
MOUNT VERNON, IOWA - OCTOBER 7: Former Secretary of State Hillary Clinton speaks to voters during an outdoor town hall meeting at Cornell College in Mount Vernon, Iowa on Wednesday October 7, 2015. (Photo by Melina Mara/The Washington Post via Getty Images)
MUSCATINE, IOWA - OCTOBER 6: Former Secretary of State Hillary Clinton speaks to a voter before leaving a farm in Muscatine, Iowa on Tuesday October 6, 2015. (Photo by Melina Mara/The Washington Post via Getty Images)
MANCHESTER, NH - OCTOBER 05: Democratic presidential candidate Hillary Rodham Clinton holds a town hall meeting at the Manchester Community College on October 5, 2015 in Manchester, New Hampshire. Clinton spoke about the need for gun control on the wake of a mass shooting at another community college in Oregon. (Photo by Alfredo Sosa/The Christian Science Monitor via Getty Images)
DAVIE, FL - OCTOBER 02: Democratic presidential candidate Hillary Clinton speaks about gun control during her campaign stop at the Broward College Ã Hugh Adams Central Campus on October 2, 2015 in Davie, Florida. Hillary Clinton continues to campaign for the nomination of the Democratic Party as their presidential candidate. (Photo by Joe Raedle/Getty Images)
WASHINGTON, DC - SEPTEMBER 19: Hillary Clinton attends the Phoenix Awards Dinner at the 45th Annual Legislative Black Caucus Foundation Conference at Walter E. Washington Convention Center on September 19, 2015 in Washington, DC. (Photo by Earl Gibson III/Getty Images)
MANCHESTER, NH - SEPTEMBER 19: Democratic presidential candidate Hillary Clinton claps on stage during the New Hampshire Democratic Party Convention at the Verizon Wireless Center on September 19, 2015 in Manchester, New Hampshire. Challenger for the democratic vote Sen. Bernie Sanders (I-VT) has been gaining ground on Clinton in Iowa and New Hampshire. (Photo by Scott Eisen/Getty Images)
PORTLAND, ME - SEPTEMBER 18: Hillary Clinton brings her Democratic presidential campaign to Maine for the first time, speaking at King Middle School. Clinton is welcomed as she is introduced at the event. (Photo by Derek Davis/Portland Press Herald via Getty Images)
CEDAR RAPIDS, IA - SEPTEMBER 7: Democratic Presidential hopeful Hillary Clinton takes time to meet supporters and take photos at the Annual Hawkeye Labor Council AFL-CIO Labor Day picnic on September 7, 2015 at Hawkeye Downs in Cedar Rapids, Iowa. Clinton spent a busy Labor Day weekend in Iowa, meeting supporters throughout the state while trying to maintain a lead over Bernie Sanders for the Democratic nomination. (Photo by David Greedy/Getty Images)
US Democratic presidential candidate Hillary Clinton takes part in a discussion after speaking about the Iran nuclear deal at the Brookings Institution in Washington, DC, on September 9, 2015. Clinton expressed firm support for the nuclear accord with Iran, calling it flawed but still strong. Clinton added that the agreement must be strictly enforced and said that if elected president next year, she would not hesitate to use military force if Iran fails to live up to its word and tries to develop a bomb. AFP PHOTO/NICHOLAS KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
PORTSMOUTH, NH - SEPTEMBER 5: Democratic presidential candidate Hillary Clinton and U.S. Senator Jeanne Shaheen take an off the schedule stop in the River Run Bookstore before shaking hands with onlookers on September 5, 2015 in Portsmouth, New Hampshire. (Photos by Charles Ommanney/The Washington Post via Getty Images)
PORTSMOUTH, NH - SEPTEMBER 5: Democratic Presidential candidate Hillary Clinton receives an endorsement from U.S. Senator Jeanne Shaheen (D-NH) September 5, 2015 in Portsmouth, New Hampshire. Clinton attended a Women for Hillary event at Portsmouth High School. (Photo by Darren McCollester/Getty Images)
PORTSMOUTH, NH - SEPTEMBER 5: Democratic Presidential candidate Hillary Clinton walks downtown Portsmouth and takes pictures with people September 5, 2015 in Portsmouth, New Hampshire. Clinton attended a Women for Hillary event at Portsmouth High School earlier in the day and received an endorsement from U.S. Senator Jeanne Shaheen (D-NH). (Photo by Darren McCollester/Getty Images)
LAS VEGAS, NEVADA - AUGUST 18: Former Secretary of State Hillary Clinton answers questions from journalists after speaking to north Las Vegas voters at a town hall meeting in Las Vegas, on Tuesday, August 18, 2015. The former Secretary was answering questions about emails sent and received a private server system, now in question, while she was the Secretary of State. (Photo by Melina Mara/The Washington Post via Getty Images)
UNITED STATES - August 15: Democratic presidential candidate Hillary Rodham Clinton greets fairgoers as she tours the Iowa State Fair in Des Moines, Iowa, on Saturday, August 15, 2015. (Photo By Al Drago/CQ Roll Call)
CARROLL, IA - JULY 26: Democratic presidential hopeful and former Secretary of State Hillary Clinton speaks to guests gathered for a house party on July 26, 2015 in Carroll, Iowa. Although Clinton leads all other Democratic contenders, a recent poll had her trailing several of the Republican candidates in Iowa. (Photo by Scott Olson/Getty Images)
CHICAGO, IL - MAY 20: Democratic presidential hopeful and former Secretary of State Hillary Clinton arrives for a meeting with parents and child care workers at the Center for New Horizons on May 20, 2015 in Chicago, Illinois. Clinton arrived in Chicago after campaigning Monday and Tuesday in Iowa. (Photo by Scott Olson/Getty Images)
LAS VEGAS, NV - MAY 05: Democratic presidential candidate and former U.S. Secretary of State Hillary Clinton (C) poses with students and faculty after speaking at Rancho High School on May 5, 2015 in Las Vegas, Nevada. Clinton said that any immigration reform would need to include a path to 'full and equal citizenship.' (Photo by Ethan Miller/Getty Images)
NEW YORK, NY - APRIL 23: Hillary Rodham Clinton (L) and actress Maggie Gyllenhaal attend the 2015 DVF Awards at United Nations on April 23, 2015 in New York City. (Photo by Michael Stewart/FilmMagic)
NEW YORK, NY - APRIL 29: Democratic presidential hopeful and former Secretary of State Hillary Clinton speaks during the David N. Dinkins Leadership and Public Policy Forum at Columbia University April 29, 2015 in New York City. Clinton addressed the unrest in Baltimore, called for police body cameras and a reform to sentencing. (Photo by Kevin Hagen/Getty Images)
Hillary Clinton announced her campaign for president on Sunday April, 12, 2015 with a video on YouTube.
(Screenshot from YouTube)
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Clinton has come under fire for using a private email account and server at her home in New York state for official emails when she was America's top diplomat between 2009 and 2013.
Critics, including likely Republican presidential election rival Donald Trump, say she endangered government secrets and evaded transparency laws but the former first lady denies any wrongdoing.
Judicial Watch brought a lawsuit against the State Department to gain access to records related to a Clinton aide's employment. The Federal Bureau of Investigation is also probing her email arrangement.
"This is a very great victory for transparency and, despite the best efforts of the Obama administration and the Clinton camp, it looks like we might finally get some answers under oath about the Clintons' illicit email system," said Tom Fitton, president of Judicial Watch.
Sullivan gave Judicial Watch permission to take testimony from close Clinton aide Huma Abedin and others.
They may be asked about the creation and operation of the private server but nothing unrelated to "whether State conducted an adequate search" in response to Judicial Watch's request for the emails, according to the court order.
It is not typical for a judge to grant discovery to a plaintiff in a Freedom of Information Act case, but Sullivan said in the order that the question remained whether the State Department provided all relevant documents to Judicial Watch.