Senator Mitch McConnell—perennial enemy of all attempts to limit the role of money in politics—has been on the attack again. This time, U.S. Supreme Court nominee Elena Kagan is in Mr. McConnell’s cross hairs. The Senate Republican leader from Kentucky says nominee Kagan is hostile to the First Amendment because while serving as solicitor general she defended a 63-year-old law that bans the use of the corporate money in federal elections. In the Citizens United case, the stakes could not have been higher: The case asked the Court to decide whether corporate money should be allowed in American elections? Ms. Kagan argued yes, corporate money should be kept on the sidelines.

Argument She Did Not Make

Anomalously, the Supreme Court heard two oral arguments in Citizens United. The first time around, the case was not argued by Ms. Kagan (she had not yet been confirmed), but instead by a career attorney in the solicitor’s office. Unfortunately, he fell into a trap laid by Justice Samuel Alito Jr. The case, as some may remember, raised the very limited legal question of whether a pay-per-view movie hostile to Hillary Rodham Clinton made by a non-profit organization, but paid for with some for-profit corporate money, should be kept off the air during the 30 days before a presidential primary, per the requirements of a 2002 campaign finance law. But during the first oral argument, the government’s lawyer conceded to Justice Alito that if the Court ruled as he was urging, the government could have the authority to ban books paid for with corporate funds. As he stated, “We [the government] could prohibit the publication of the book using the corporate treasury funds.”

The rehearing of the Citizens United case was Solicitor General Kagan’s first oral argument before the Supreme Court. During the argument, she explicitly disavowed the position staked out by her predecessor, stating “[t]he government’s answer has changed…nobody in Congress, nobody in the administrative apparatus has ever suggested that books pose any kind of corruption problem.”

Argument She Did Make

Ms. Kagan skillfully argued instead that shareholders have an important interest in maintaining the decades-old ban on corporate money in politics. But the conservative block on the Court wasn’t buying it. Chief Justice John Roberts posited: “Your shareholder protection rationale, isn’t it extraordinarily paternalistic for the government to take the position that shareholders are too stupid to keep track of what their corporations are doing and can’t [they] sell their shares or object in the corporate context if they don’t like it?”

Ms. Kagan responded: In “a world in which most people own stock through mutual funds, in a world where people own stock through retirement plans in which they have to invest, they have no choice, I think it’s very difficult for individual shareholders to be able to monitor what each company they own assets in is doing.”

In other words, Ms. Kagan stood up for the rights of the nearly 50 percent of American households who own stocks and would like to keep their investments out of the political sphere. Unfortunately, the Court did not agree with Ms. Kagan. Its ruling in favor of corporate spending enables corporations to hijack investors’ money for use in political campaigns.

Argument She Should Have Made

Ms. Kagan’s argument before the Court is now drawing fire from the left, but for a different reason. Critics argue that she too quickly abandoned a legal rationale that had maintained the separation between corporate money and politics since 1990. These critics argue that she did not give a full-throated defense of the 1990 case which was on the chopping block, Austin v. Michigan Chamber of Commerce, 494 U.S. 652.

In Austin (1990) and again in McConnell v. Federal Election Commission, 540 U.S. 93 (2003), the Supreme Court had upheld an expansive anti-distortion rationale of corruption as a compelling state interest to keep corporate money out of politics. By not arguing that Austin should be upheld, Ms. Kagan, to her critics, allowed the 5-4 conservative majority to run rough shod over not only the corporate ban on corporate spending, but also over the real danger that big money in elections would distorts the political process. Instead, the Court held in Citizens United v. Federal Election Commission, 120 S. Ct. 876, that the only reason Congress can rely on to regulate money in politics is to prevent quid pro quo corruption—a very thin reed for Congress to use in the future.

Coverage in the press has surmised that Ms. Kagan abandoned Austin and its anti-distortion rationale in the hopes of peeling off a vote in her favor. Unfortunately for all concerned with the pernicious effect of corporate money on politics, there was no one on the Court to sway. The cork on the champagne bottle of corporate funding popped on Jan. 21, when the court handed down its Citizens United decision.

Senator McConnell is caricaturing Ms. Kagan’s role in Citizens United for his own political reasons. She didn’t go hard left in her arguments and she never argued for banning books. What she did do was stand up for American voters and shareholders and try to keep corporate dollars from overwhelming our political system. For that she should be commended; not vilified.

Ciara Torres-Spelliscy is an attorney for the Brennan Center for Justice.