US President Donald Trump's choice for the Supreme Court questioned whether a ruling legalising abortion was settled law, emails show.
Brett Kavanaugh, 53, made the comments while working as a lawyer in 2003 for then-President George W Bush.
His record is being closely examined as his appointment is seen as likely to tip the court towards the right.
The Supreme Court is America's highest and has the final word on many contentious matters.
Judges are appointed for their lifetime and getting his nominee approved would mark a victory for President Trump and his supporters.
The email shows Mr Kavanaugh considering an opinion piece which states "it is widely accepted by legal scholars across the board that Roe v Wade and its progeny are the settled law of the land", referring to the landmark ruling that legalised abortion in the US.
In response, Mr Kavanaugh says: "I am not sure that all legal scholars refer to Roe as the settled law of the land at the Supreme Court level since court can always overrule its precedent, and three current justices on the court would do so."
The nominee is currently attending day three of a four-day confirmation hearing in Washington.
Asked about the document, he repeated what he said on Wednesday that Roe v Wade was an "important precedent of the Supreme Court, reaffirmed many times".
While campaigning for the presidency, Mr Trump promised to appoint pro-life judges, raising the possibility of Roe v Wade being overturned.
What else do the emails show?
Thursday's committee hearing began with Democrats threatening to release emails from Mr Kavanaugh detailing his time working as a White House lawyer.
The emails are not classified but are considered "committee confidential", meaning they are only intended for senators and their staff, not the general public.
Democrats, who have argued that the hearing should be delayed to allow them to completely review all of Mr Kavanaugh's records, released the emails after disputing the White House's claim that they pertain to national security.
Emails released by Democrat Corey Booker show Mr Kavanaugh expressing concern about law enforcement's ability to conduct "race-neutral" policing policies in the years after the 11 September attacks.
The 12-page email thread occurred under the subject line "racial profiling".
Hawaii Democrat Mazie Hirono released emails showing the judge questioning whether native Hawaiians should have access to the same programmes available to other indigenous groups.
Republicans bristled at the Democrats' unusual move, with Texas Senator John Cornyn accusing Mr Booker of "conduct unbecoming of a senator".
"Running for president is not an excuse for violating the rules of the Senate," said Mr Cornyn, calling the move "irresponsible and outrageous".
Mr Booker said he was aware he could be ousted from the Senate over his decision, but struck a defiant tone.
"Bring the charges, go through the Senate process to take on somebody you said is unbecoming to be a Senator," he told his Republican colleagues.
"Let's go through that process because I think the public should understand that at a moment someone is up for a lifetime appointment."
What else has been said at the hearing?
On Wednesday, Mr Kavanaugh refused to answer whether he thought presidents can pardon themselves if they face criminal charges.
In one exchange with Democrat Kamala Harris, he declined to answer whether he had had discussions about the special counsel's probe of alleged Russian meddling in the 2016 election.
Special Counsel Robert Mueller is also investigating whether members of the Trump White House sought to obstruct the inquiry.
"No-one is above the law in our constitutional system," he replied when asked by a Republican whether he would have any trouble ruling against the president who appointed him.
Mr Trump has criticised the special counsel's investigation as a "witch hunt" and insists he is permitted to pardon himself.