Liberals are still seething over the way the Supreme Court reaffirmed the Citizens United decision in the Montana campaign finance law case where state restrictions on political spending were rightly overruled. But this defense of free speech rights will not go unanswered by a Democratic Party that thinks allowing citizens and groups to support ideas and candidates is a scandal. That’s why New York’s left-wing attorney general is launching a brazenly partisan attack on the right of political speech in the guise of an investigation of alleged violations of the tax code.

New York Attorney General Eric Schneiderman is a hard-line liberal who has been itching to use his post to both fight for restrictive campaign finance laws and to garner the publicity that will enable him to advance his career. On the surface, Schneiderman is merely conducting a probe into contributions to tax-exempt groups. But by focusing his attention on the U.S. Chamber of Commerce, a pro-business conservative group, the political intent of the investigation is obvious.

Schneiderman isn’t the first Democrat to try to use the post of New York attorney general to conduct politicized prosecutions to burnish his reputation. The now disgraced Eliot Spitzer’s attacks on Wall Street paved the way for his path to the governorship of the state. Current Governor Andrew Cuomo also used the post in this manner. But Schneiderman is not just another New York Democrat on the make. He’s an ideologue who campaigned on support for campaign finance laws and now appears to be willing to use his power to conduct an inquisition of conservative non-profits that will make him the darling of the left around the nation.

There is no obvious evidence of wrongdoing of any kind or legal violations on the part of the National Chamber Foundation, the Starr Foundation or the Chamber itself, though all have received subpoenas from Schneiderman. There is nothing unusual in the financing of some of the group’s activities by non-profit foundations. But what they are guilty of is being conservative groups in the crosshairs of leftist opponents seeking to brand their donations as somehow running afoul of the laws governing non-profits because of their advocacy for tort-reform, a cause that doesn’t sit well with Democratic constituencies such as trial lawyers and unions.

The same amorphous questions could be put to any non-profit involved in public advocacy. But political observers on both sides of the aisle understand that when probes like this are conducted, the only possible motivation is not respect for the law but a desire to criminalize political opponents.

Local political payback is also involved here because the Starr Group is headed by former AIG chair Maurice R. Greenberg, who was driven out of the country by a vindictive and ultimately failed prosecution launched by Spitzer during his climb up the greasy pole of New York politics.

Above all, the Schneiderman fishing expedition is an attempt to supply some proof that the Citizens United decision has unleashed a wave of political corruption, a key talking point for liberal critics of the landmark free speech case. In spite of their allegations that allowing organizations, including labor unions and other left-wing groups, to spend to promote their ideas, has despoiled politics, all Citizens United has done is to increase the amount of political speech. That is antithetical to leftists who wish to regulate the marketplace of ideas and repress the efforts of grassroots groups to fight back against big government initiatives.

Given the almost unlimited power of Schneiderman to conduct his probe, conservative groups should expect to be harassed in the coming months and years. But while Schneiderman and his cheerleaders in the mainstream press will represent this investigation as a public spirited attempt to rein in corruption, there can be no doubt that it is merely an unprincipled political witch hunt whose purpose is to cripple the efforts of conservative groups.