WASHINGTON — Sen. Cory Booker was mocked by critics for daring his colleagues to "bring it" and try to expel him for releasing emails that Republicans on the Judiciary Committee had deemed confidential during Supreme Court nominee Brett Kavanaugh's confirmation hearings.

But that mocking, mostly about his invocation of the rebellious Roman slave Spartacus, may be the only penalty Booker faces.

Many of his critics say Booker was just showboating for a future presidential campaign and did not break the rules at all when he released emails after a Sept. 6 committee hearing. That's because the "committee confidential" classification on the first batch of documents he released had already been lifted when he put them out.

Indeed, the classification had been lifted even before Booker vowed to release the emails and got into a back-and-forth with Sen. John Cornyn, R-Texas. Cornyn said senators who couldn't follow the rules did not deserve to be on the committee or in the Senate, and Booker taunted him to "bring it," a line he repeated in several interviews later and on "The Tonight Show Starring Jimmy Fallon."

But while the first batch he released was already public, Booker had broken the rules the night before when he read from them during his questioning of Kavanaugh. He was challenged at that point by Sen. Mike Lee, R-Utah, and moved on to another issue.

And Booker released dozens more pages of emails Kavanaugh sent as an aide to President George W. Bush that had not been cleared for release, all to emphasize what Booker said was a "sham" process of concealing parts of Kavanaugh's record during the rushed public hearings.

The first batch included emails with the subject line "racial profiling," which Kavanaugh implied could happen for an interim period until new race-neutral procedures could be developed, when new airport screening procedures were created after 9/11.

Later releases included emails about Kavanaugh's role in a judicial nomination that Booker said contradicted what the judge had told the committee during an earlier confirmation hearing. And another batch showed Kavanaugh's interactions with a Republican Senate aide who had accessed Democrats' files about nominations while Kavanaugh was trying to steer Bush nominees through the Senate.

A conservative legal activist group, Judicial Watch, agreed that Booker broke the rules. It sent a letter Sept. 12 to the Select Committee on Ethics asking that Booker be punished.

“Senator Booker, in an absurd invocation of ‘Spartacus,’ explicitly invited his expulsion from the Senate,” Judicial Watch President Tom Fitton said in a news release. “Will the Senate assert the rule of law in the Booker case or allow mob rule to be the new standard?”

But that complaint could be as far as things go.

"We've received no response, and I don't believe the rules require a response," Fitton said through a spokeswoman Monday. "The committee can be a black hole for complaints they don't want to act on."

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Unlike the House, which has a process for the public to file complaints about members that ensures at least some examination of whether there's merit or not, the Senate's rules do not. The ethics committee is also the only one in the Senate where there's an equal number of members from each party, meaning nothing can happen without at least some bipartisan support.

"In a totally opaque process. The committee staff will take a first look at it," said Meredith McGehee, executive director of the government reform advocacy group Issue One, who has spent decades pushing for changes to ethics oversight.

"The staff will then make a recommendation to the bipartisan committee chairs, and at that point there could be a direction to staff to do further investigation. I would say the likelihood of that is slim, given this is mostly a political question," McGehee said.

It was never likely that Booker would actually face expulsion for what he did. That penalty was last imposed on senators from Confederate states that were at war with the union, and it requires a vote by two-thirds of the Senate, or 67 members.

That means Democrats would have to join any effort to oust Booker, and most of his fellow Democrats on the committee all spoke up in support of him at the Sept. 6 hearing. This led to Booker's tangled quote, "This is about the closest I'll probably ever have in my life to an 'I am Spartacus' moment."

Making further action even more unlikely is that one of the Democrats who spoke up on Booker's behalf that day was Sen. Chris Coons of Delaware, who also happens to be co-chairman of the ethics committee.

"I agree with Senator Booker," Coons said at the Sept. 6 hearing. "This confirmation is too important for us to conceal documents that may reveal the nominee's views, and I think we shouldn't be proceeding under these grounds."