delivered the opinion of the Court.
When the Texas Legislature adjourned without enacting redistricting plans for the Texas Senate and Texas House of Representatives, that responsibility was constitutionally delegated to the Legislative Redistricting Board (“LRB”). Tex. Const, art. Ill, § 28. The LRB accordingly formulated senate and house redistricting plans, which various parties have challenged in the Travis County district court. This mandamus proceeding arises out of the plaintiffs’ attempt to depose three members of the LRB and their aides regarding their “consideration of and/or formulation of’ those redistricting plans. We must decide whether legislative immunity protects the LRB members and their aides from the plaintiffs’ requested discovery. We hold that the LRB members, in apportioning legislative districts pursuant to constitutional mandate, were acting in a legislative capacity and are cloaked, as are their aides, with legislative immunity. We also hold that this immunity encompasses an evidentiary and testimonial privilege, which the plaintiffs have failed to overcome by demonstrating extraordinary circumstances that arguably might warrant an exception. Accordingly, the trial court abused its discretion in denying the LRB members’ motion to quash. Because the relators have no adequate remedy by appeal, we conditionally issue the writ of mandamus.
I. Background
The Texas Constitution requires the Legislature to apportion the state into senatorial and representative districts after each United States decennial census. Tex. Const, art. Ill, § 28. Section 28 mandates that the Legislative Redistricting Board shall make such an apportionment if the Legislature fails to do so. Id. The LRB constitutionally comprises five members, the Lieutenant Governor, the Speaker of the House of Representatives, the Attorney General, the Comptroller of Public Accounts, and the Commissioner of the General Land Office. Id. Once executed and filed with the Secretary of State, the LRB’s apportionment “shall have force and effect of law.” Id.
The 77th Legislature adjourned sine die without enacting a redistricting plan. Accordingly, that task fell to the LRB, which convened and adopted a redistricting plan. Thirteen Texas residents 1 filed this suit alleging that the LRB’s plan is constitutionally and statutorily infirm and re *859 questing court intervention to protect their constitutional and voting rights. The plaintiffs sought to depose three board members and their chief legislative aides: (1) Attorney General John Cornyn, and his aide, Special Attorney General John Greytok; (2) Comptroller Carole Keeton Rylander, and her aide, Tracy Wurzel, Manager of the Legislative Analysis Group of the Comptroller of Public Accounts; and (3) Land Commissioner David Dewhurst, and his aide, Chief Clerk/Deputy Land Commissioner Larry Soward. The deposition notices seek documents and testimony regarding
all data entries, plans, partial plans and calculations performed on or in connection with the State of Texas “Red Apple” redistricting system/program, that relate to [sic] any manner to the consideration of and/or formulation of redistricting plans for the Texas Senate and the Texas House of Representatives.
The relators, Governor Rick Perry and former Secretary of State Henry Cuellar, filed motions to quash the deposition notices, contending that legislative immunity absolutely shields the LRB members and their aides from discovery in this matter. The trial court denied the motion, and the relators sought mandamus relief from the court of appeals. The court of appeals denied their mandamus petition on October 5, 2001. The relators now seek mandamus relief in this Court.
II. Discussion
Texas and federal courts have recognized that individuals acting in a legislative capacity are immune from liability for those actions.
See, e.g., Bogan v. Scott-Harris,
[T]he threat of liability can create perverse incentives that operate to inhibit officials in the proper performance of their duties. In many contexts, government officials are expected to make decisions that are impartial or imaginative, and that above all are informed by considerations other than the personal interests of the decisionmaker. Because government officials are engaged by definition in governing, their decisions will often have adverse effects on other persons. When officials are threatened with personal liability for acts taken pursuant to their official duties, they may well be induced to act with an excess of caution or otherwise to skew their decisions in ways that result in less than full fidelity to the objective and independent criteria that ought to guide their conduct.
Forrester v. White,
Legislative immunity derives largely from the Speech and Debate Clauses of the Texas and federal constitutions, which, in turn, embody fundamental separation-of-powers tenets.
See
U.S. Const, art. I, § 6; Tex. Const, art. Ill, § 21;
United States v. Johnson,
Courts have extended the legislative immunity doctrine beyond federal and state legislators to other individuals performing legitimate legislative functions.
See, e.g., Bogan,
We have no doubt that the LRB members were acting in a legislative capacity when they apportioned senatorial and representative districts pursuant to constitutional mandate. Under our Constitution, the LRB effectively stepped into the Legislature’s shoes after that body failed to act.
See
Tex. Const, art. Ill, § 28. Moreover, our Constitution specifically provides that the LRB’s apportionment “shall have force and effect of law.”
Id.
No act is more fundamentally legislative than lawmaking itself.
See Bogan,
Relators contend that, once we have determined that legislative immunity applies, the immunity is absolute and without exception. There are cases that arguably support that contention, at least so far as immunity from liability is concerned.
See, e.g., Bogan,
In
Arlington Heights,
the Supreme Court discussed the type of proof required to establish an Equal Protection violation. To show an Equal Protection violation, proof of racially discriminatory intent is required.
Arlington Heights,
judicial inquiries into legislative or executive motivation represent a substantial intrusion into the workings of other branches of government. Placing a de-cisionmaker on the stand is therefore “usually to be avoided.”
Id.
at 268 n. 18,
Thus,
Arlington Heights
suggests that there could be a circumstance, albeit extraordinary, that might constrict the grant of legislative immunity when, as in this case, a plaintiff alleges that the action violates the Equal Protection Clause.
See also Marylanders,
To support their position, the plaintiffs cite a number of cases in which officials have testified about redistricting efforts.
See Seamon v. Upham,
III. Conclusion
We hold that the trial court abused its discretion in denying the relators’ motion to quash. A party has no adequate remedy by appeal when the trial court erroneously orders the disclosure of privileged information.
TransAmerican Natural Gas Corp. v. Flores,
Notes
. The plaintiffs are David Brown, David O. Zambrano, Joy Smith, Vivian Harris, Tony Campos, Ed Gonzales, Margaret P. Rodriguez, Michael Moon, Dan Pedroza, Pauline Dixon, Raphael Quintanilla, Hargie Faye Savoy, and Ralph McCloud.
. Our research has revealed only one instance in which a person acting in a legislative capacity has been compelled to testify.
See Marylanders,
