A Senate hearing Tuesday could become the first step to creating a dictionary entry for “Durbinism,” named after Sen. Dick Durbin, D-Ill.

Dictionary.com defines McCarthyism as “the practice of making unfair allegations or using unfair investigative techniques, especially in order to restrict dissent or political criticism.” Durbin’s new twist is to disguise efforts to restrict dissent under the veneer of what he calls “disclosure” and “accountability” to help enforce his political orthodoxy.

To recipients of a letter Durbin sent to about 300 groups in connection with his hearing, the intimidating message was clear: Stop supporting the American Legislative Council (ALEC), a bipartisan group of conservative-leaning state legislators. Because ALEC once supported stand-your-ground laws, Durbin wants to scare off donors to the group.

Ironically, Durbin is using his perch as chairman of the Judiciary Subcommittee on Constitution, Civil Rights and Human Rights to threaten our First Amendment freedoms of speech and association.

Durbin was quoted in a news account on the letters saying, “my concern is with the lack of transparency. As a public official, when I take a position, I stand up to explain and defend it. I file annual financial disclosures, campaign finance reports and have to face the scrutiny of public opinion.”

The legitimate purpose of disclosure is to allow citizens to monitor elected officials to prevent corruption. Durbinism is the concept of using disclosure to allow elected officials to monitor citizens and suppress dissent.

The aim of this new form of disclosure is to compile lists that can be used to gin up boycotts and threats to the supporters of groups that offend elected officials — indeed, this is already being done.

Tuesday’s hearing is part of a disturbing pattern by Durbin and his allies to use disclosure and other tactics to intimidate. Durbin is a long-time supporter of the DISCLOSE Act, a partisan bill that is aimed more at silencing political opponents than it is at creating any meaningful disclosure of election activities.

As Sen. Charles Schumer, D-N.Y., warned when the first version of it was introduced, “the deterrent effect should not be underestimated.”

In 2010, Durbin sought to stop conservative groups from using their First Amendment rights under the Supreme Court’s Citizens United decision by writing the IRS to ask for audits of conservative groups.

Such a letter from the president or his staff would have been illegal, and the Durbin letter appears contrary to Senate ethics rules, which bar senators from making demands of this type to an agency.

Durbin was not the only senator to pressure the IRS. These letters likely played a role in creating the IRS scandal, which has devastated the agency’s reputation and could impact its ability to collect taxes.

The First Amendment guarantees the right to speak without fear of retribution from elected officials. Durbin is treading on dangerous ground. Recipients of his letter may fear a future demand they testify under oath to his committee on their donations. He should understand that he is a public servant, not a public master.

Justice Oliver Wendell Holmes wrote that “the ultimate good desired is better reached by free trade in ideas — that the best test of truth is the power of the thought to get itself accepted in the competition of the market, and that truth is the only ground upon which their wishes safely can be carried out.”

Sen. Durbin would do well to heed this advice by focusing on making the case for his policies, rather than abusing his powers to intimidate groups whose policies he disagrees with.

David Keating is president of the Center for Competitive Politics, which works to defend First Amendment political speech rights.