Washington (CNN) -- Justice Antonin Scalia, a popular and entertaining speaker at various forums around the world, has one of the busiest schedules off the bench. But a closed-door address the conservative justice is scheduled to give Monday afternoon has attracted controversy, partly because of who is sponsoring the event.

The Tea Party Caucus, an informal congressional body, had invited the 74-year-old to talk informally with legislators, the first in what leaders are billing as regular "conservative constitutional seminars."

The event was designed as a "teaching event" only for members of Congress, and no cameras or reporters would be allowed to cover it. Scalia's scheduled one-hour topic will be "separation of powers."

"It is a special privilege to have him address the first of what will be regular seminars featuring constitutional scholars," Rep. Michele Bachmann, R-Minnesota, chairwoman of the Tea Party Caucus, said in December. "In his 24 years of service on the high court, Justice Scalia has distinguished himself by his 'originalist' approach to constitutional interpretation."

Her office said Friday that about 40 members were expected to attend.

Bachmann promised that the seminars would be held at least twice monthly for members of Congress. They are being organized in conjunction with the caucus, which she founded in July, and the Congressional Constitution Caucus, which is chaired by Reps. Scott Garrett, R-New Jersey, and Rob Bishop, R-Utah.

Political sources say Bachmann personally came to see Scalia in his chambers late last year and offered the invitation, which he accepted.

The Tea Party movement, a populist grass-roots coalition with mostly politically conservative members, has growing in popularity in the past few years. The various affiliated groups had some success electing members of Congress in the November midterms who shared many of the positions on taxation, budget deficits and constitutional interpretation.

Many Tea Party activists find Scalia's "originalist" views on the Constitution to be especially appealing. As he once explained his views, "It's simple: Our manner of interpreting the Constitution is to begin with the text, and to give that text the meaning it bore when it was adopted by the people." He has rejected suggestions that abortion and gay rights -- among other things -- were "guaranteed" in the Constitution. That view had left him often in dissent in his early years on the high court, when it was a mostly moderate-left bench.

Scalia was nominated to the high court in 1986 and has been among its most conservative, and articulate, members.

Bachmann has said that all members of Congress, including Democrats, are invited to the Scalia event, even though it is billed as a "conservative constitutional seminar."

Neither the Supreme Court nor the justice's chambers had any comment on the upcoming event. It was unclear whether other members of the high court would be invited to future seminars.

Critics of Scalia's appearance said it could raise the appearance of impropriety and lead to political polarization over the high court.

The speech "suggests an alliance between the conservative members of the court and the conservative members of Congress," Jonathan Turley, a law professor at George Washington University, said on his legal blog. He said the justice was showing "exceedingly poor judgment."

A New York Times editorial called the arrangement "outlandish" and "dismaying."

But Edward Whelan, a former Scalia law clerk and head of the Ethics & Public Policy Center, downplayed any concern.

"Does he think it's improper for any justice ever to speak to any group of members of Congress who might be perceived as sharing the same general political disposition?" he asked in a posting on the National Review's Bench Memos blog. "My guess is that, schedule permitting, Scalia would be happy to speak on the same topic to any similar group of members of Congress who invited him."

Substantive meetings between members of the high court and legislators are not unusual. Just this week, Justice Stephen Breyer addressed a private bipartisan retreat for House Judiciary Committee members. The justice had been chief counsel to the Senate Judiciary Committee from 1979 to 1980 under then-Chairman Edward Kennedy, D-Massachusetts.

The House committee is now chaired by conservative Rep. Lamar Smith, R-Texas, who invited Breyer to talk about achieving bipartisan success.

Scalia's views on separation of powers may leave some fellow conservatives uneasy when he addresses them Monday. In past remarks, he has voiced concern about congressional interference in federal judicial matters.

In a May 2006 speech on Capitol Hill, he said it was not proper for Congress "to direct the Supreme Court" in how it does its job. In particular, Scalia said, lawmakers should not pass bills forbidding judges from using foreign law in its decision-making.

"It's none of your business," he said, referring to Congress. "No one is more opposed to the use of foreign law than I am, but I'm darned if I think it's up to Congress to direct the court how to make its decisions."

At the same time, the justice added that he has long opposed trying to legislate from the bench and that courts sometimes have taken on too much regulatory power best left to Congress.

"All you have to do is pass the statute, and it's not up to us to tell you otherwise," he added. "Let us make our mistakes just as we let you make yours," which brought laughter from the crowd.

After taking over the House of Representatives this month, one of the first orders of business for GOP leaders was to set aside time for a full public reading of the U.S. Constitution, on the chamber floor. Tea Party-backed Republicans in Congress have also proposed a measure requiring that all bills submitted for approval be accompanied by a statement that explains why they are constitutional.

The State of the Union address by President Obama is set for the day after Scalia's remarks to the Tea Party Caucus. Scalia has been a regular no-show to the speech.

CNN Congressional Producer Deirdre Walsh contributed to this report.