Kavanaugh was arguing for doing all that is possible to make policies and procedures "race-neutral".
"It was a gut punch for me", he said, and he was "shocked, disappointed, angry".
Durbin says Trump has "shown disrespect for the rule of law over and over again".
To win confirmation, Republicans can only afford to lose one of their own if all Democrats vote against Kavanaugh.
US President Donald Trump's Supreme Court nominee has declined to say whether he thinks sitting presidents can be made to comply with a legal subpoena.
"No one is above the law in our constitutional system", he said.
Democrats need at least two GOP defections to have any chance of defeating the nomination.
When Kavanaugh in the memo referred to three justices willing to overturn Roe, he was referring to Justices William Rehnquist, Antonin Scalia and Clarence Thomas, who had expressed opposition.
On abortion, Kavanaugh said the landmark 1973 Roe vs. Wade decision that ensures access to abortion has been affirmed "many times".
The Kavanaugh questioning continues Thursday.
When asked about the email Thursday, Kavanaugh said he recommended the edit to the op-ed because he didn't think the draft accurately reflect the view of all legal scholars. But Trump's fellow Republicans maintain a narrow Senate majority and there are no signs of defections in their ranks, indicating Kavanaugh likely will be confirmed.
The Supreme Court is America's highest and has the final word on many contentious matters. "A judge must interpret the Constitution as written, informed by history and tradition and precedent", he said. But because it had been deemed "committee confidential" after a review, Booker was not allowed to refer to it or ask Kavanaugh questions about it. Committee chairman Sen.
On top of that, there is a large period time-from Kavanaugh's time as an associate White House counsel in the Bush administration, which he himself has called a "formative" job in shaping his career-from which very few records have been made available to the senators.
"Have you had any conversation about Robert Mueller or his investigation with anyone at that firm?"
Sen. Kamala Harris of California asked Kavanaugh late Wednesday if he had spoken about the Russian Federation investigation with anyone at the law firm founded by Marc Kasowitz, who has represented Trump.
Kavanaugh wrote in another document that some US Transportation Department affirmative action regulations used "a lot of legalisms and disguises to mask what is a naked racial set-aside".
"You just can't do everything you want in a legislative body", he said.
Harris promised to follow up with Kavanaugh on the topic.
During a marathon session on Wednesday, Kavanaugh avoided answering questions about the scope of presidential power including whether a president can pardon himself.
The Justice Department has said on two separate occasions, in 1973 and in 2000, that the president can not be charged with a crime while in office.
The article contained a blanket statement about the abortion rights decision that Kavanaugh, who faced his third day of grilling at a confirmation hearing Thursday, took exception to.
Democratic Senator Cory Booker appealed to Grassley's "sense of decency and integrity" and said the withholding of the documents by Republicans and the White House left lawmakers unable to properly vet Kavanaugh.
"The fact that there is nothing in that document that's personal information, there's nothing national security-related, the fact that it was labeled as committee confidential, exposes that this process, sir, is a bit of a sham", Booker said. "If Senator Cornyn believes that I have violated Senate rules, I openly invite and accept the consequences of my team releasing that email".
Sen. Susan Collins (R-Maine) has said she would not vote for a nominee who threatens Roe. The Supreme Court would have to rule on that question to settle the matter. A lawyer for former president George W. Bush provided 415,000 pages of documents last week, but the Trump administration chose to withhold 100,000 pages from the Senate under executive privilege.
On abortion, Mr Kavanaugh said he understood people's strong feelings and he described Roe v Wade as "an important precedent of the Supreme Court that has been reaffirmed many times". The email was sent to a Republican Senate aide. The document was partially redacted.
Heidi Heitkamp, a North Dakota Democrat, told CNN Wednesday afternoon when asked if anything she's heard so far would be considered disqualifying.
Democrats are keen to push Mr Kavanaugh on the issue, he adds.
Trump says he's pleased with his nominee's performance, and Republicans are united behind him.
Kavanaugh underwent a 12-hour session of questioning that ended late Wednesday.