OPINION
PHILLIPS, Chief Justice.
This original mandamus action involves two pre-trial discovery requests sought by [836]*836relators, plaintiffs in a medical malpractice lawsuit. The first discovery dispute involves documents which the plaintiffs seek from one of the defendants, while the second involves documents which they seek from a nonparty for impeachment purposes. As to the first matter, we hold that relators have not presented a sufficient record to demonstrate that the trial court clearly abused its discretion in failing to grant them all requested relief. As to the second, we hold that relators have an adequate remedy by appeal. Thus, mandamus is inappropriate, and we deny the writ.
The St. Paul and Aetna Records
Catherine Johanna Walker sustained brain damage at birth in January 1983. In January 1985, her parents, Charles F. and Mary Jeanette Walker, sued Dr. Paul Cri-der, the obstetrician, St. Paul Hospital, where Catherine was born, and Iris Jean White, a nurse attending at the delivery.
In August 1987, the Walkers served on St. Paul their third request for production of documents pursuant to Tex.R.Civ.P. 167. One request asked for:
Any and all writings, notes, documents, letters, etc., concerning, mentioning, alluding to, or making reference to (either directly or indirectly), the tape recorded statement given by Nurse White to an Aetna adjuster, including but not limited to any notes or entries in any Aetna adjuster’s file, any attorney’s file, or any file or writing in possession of any employee, representative or agent of St. Paul Hospital. This request is in reference to the tape recorded statement which you have been unable to locate, but which was previously requested....
St. Paul responded as follows:
In an effort to respond to this request, this Defendant again checked with all appropriate personnel and files at St. Paul Hospital and the law firm of Bailey and Williams. No such statement or taped recording was found. For the third time the Aetna Casualty and Surety Company was asked to check its records and files and a partially transcribed statement was located, a copy of which is attached. No taped recording was located.
Nearly two years later, the Walkers filed a motion to compel under Tex.R.Civ.P. 215, asserting that St. Paul failed to respond completely to the request.1 The Walkers complained that “St. Paul Hospital did not even respond to what was requested in the request for production — that is, writings, notes, and notations in the adjuster’s file or attorney’s file mentioning, alluding to, or making reference to the tape recorded statement of Nurse White.” At about the same time, the Walkers also served on Aet-na Casualty and Surety Company, St. Paul’s insurer, an “Amended Notice of Intention to Take Deposition Upon Written Questions — Duces Tecum,” seeking, among other things, the same documents. Aetna moved to quash the notice.
The trial judge appointed a special master to review the Walkers’ motion to compel and Aetna’s motion to quash. After an evidentiary hearing on September 5, 1989, the master prepared findings, which formed the basis for two extensive orders signed by the trial court on September 20, 1989. In the first order, the court found that the Walkers were “entitled to all documentation sought in [the request] from the files of Defendant St. Paul or its attorney of record, but not from the files of Aetna Insurance Company, except as they may appear in the files of St. Paul or the attorneys of record of St. Paul.” The court also stated that it “has been advised that St. Paul has supplied all documentation that is responsive to [the request], but that additional documentation will be made available [837]*837to the Court for in camera review.” The court therefore sustained the Walkers’ motion to compel “to the extent that on Friday, September 8, 1989 the Special Master will review in the Chambers of the 134th District Court the relevant portions of the St. Paul files and their attorney [sic] files, which may be in response to Plaintiff’s request....” The court, however, did not order St. Paul to produce documents from Aetna’s files for in camera inspection.2
After the master’s September 8 in camera inspection, the court ordered discovery of three additional documents from the files of St. Paul and its attorneys, which it found “relate to the matters sought in discovery and should be supplied after irrelevant portions of such documents are stricken.”
After unsuccessfully seeking relief in the court of appeals, the Walkers moved for leave to file a petition for writ of mandamus with this court, arguing that the trial court clearly abused its discretion by refusing to order St. Paul to produce the documents from Aetna’s files and by ordering that portions of the other responsive documents be stricken. The Walkers contend that the order was a clear abuse of discretion because St. Paul 1) never objected to the Walkers’ request for production, 2) had a superior right to the Walkers to compel production of the documents in Aet-na’s possession, and 3) never asked that any parts of the documents be excised.
The record before us does not include the statement of facts from the evidentiary hearing on the Walkers’ motion to compel production. Without it, we cannot determine on what basis the trial judge and the special master reached their conclusions. Since we cannot assess whether or not the trial court’s order was correct, we obviously cannot take the additional step of determining that the court’s order, if incorrect, constituted a clear abuse of discretion.
As the parties seeking relief, the Walkers had the burden of providing this Court with a sufficient record to establish their right to mandamus relief. Since an evidentiary hearing was held, the Walkers had the burden of providing us not only a petition and affidavit, see Tex.R.App.P. 121(a)(2)(C) and (F), but also a statement of facts from the hearing. See, e.g., Cameron County v. Hinojosa, 760 S.W.2d 742, 744 (Tex.App.—Corpus Christi 1988, orig. proceeding); Greenstein, Logan & Co. v. Burgess Mktg. Inc., 744 S.W.2d 170, 177 (Tex.App.—Waco 1987, writ denied); see also Western Casualty & Surety Co. v. Spears, 730 S.W.2d 821, 822 (Tex.App.—San Antonio 1987, orig. proceeding).3 Having failed to meet this burden, the Walkers have not provided us with a record upon which they can establish their right to mandamus relief against St. Paul.
The Obstetrics Faculty Records
The second discovery dispute arises out of the Walkers’ attempt to secure documentary evidence to impeach one of the defendants’ expert witnesses, Dr. Larry Gilstrap, a faculty member in obstetrics at the University of Texas Health Science Center at Dallas (“the Center”). Gilstrap testified at his deposition that expert witness fees earned by obstetrics faculty members are deposited into a “fund” in the obstetrics “billing department”; that obstetrics faculty members get paid “indirectly” from this fund; that the fund is handled by Judy Wagers, a Center employee; and that he was unaware of any obstetrics department policy restricting faculty members from testifying for plaintiffs in medical malpractice cases.
[838]*838Thereafter, the Walkers noticed Wagers’ deposition, requesting that she provide all documents regarding (1) the operation of the above-mentioned “fund” from 1985 to 1988; and (2) limitations placed upon obstetrics faculty members relating to their testimony in medical malpractice cases. The Center, on behalf of Wagers, moved to quash the notice, arguing that the request for documents was “vague and overly broad” and that production would be “costly and burdensome.”
Two months later, in an unrelated lawsuit, the Walkers’ counsel deposed Dr. Alvin L. Brekken, another obstetrics faculty member at the Center. Dr. Brekken testified that the obstetrics department’s official policy, distributed in writing to all faculty members, requires a doctor to obtain authorization from other faculty members before testifying for any plaintiff in a medical malpractice case. Based on this testimony, the Walkers sought a court order to depose Wagers and obtain the requested documents.
After reviewing the Gilstrap and Brekken depositions and pleadings of counsel, the trial court ordered the Center to produce the documents for in camera review by the special master. Subsequently, in her September 20, 1989 order, the trial judge denied the discovery, stating in part:
[S]uch requested discovery is improper pursuant to the Rulings of the Supreme Court of Texas in Russell v. Young [452 S.W.2d 484 (Tex.1970) ], as the potential witness is not a party to the suit and the records do not relate to the subject matter of the suit, but are sought solely for the purpose of impeachment, according to the Plaintiffs’ pleadings.
Although noting that some of the documents “would be relevant to this cause of action,” the court nevertheless denied discovery because “all such documents are controlled by the Russell decision.”
In Russell, a party sought wholesale discovery of financial records of a potential medical expert witness who was not a party to the lawsuit.4 The documents requested did not relate directly to the subject matter of the suit, but were sought solely in an attempt to impeach the potential witness by showing bias or prejudice. The credibility of the witness, however, had not yet been put in doubt. Under these circumstances, we held that the documents were not discoverable, and we directed the trial court to vacate its order allowing the requested discovery. 452 S.W.2d at 435. We reasoned that “[tjhere is ... a limit beyond which pre-trial discovery should not be allowed.” Id. at 437.
The present case is distinguishable. Here, the Walkers presented to the trial court evidence of a specific circumstance— the Center’s policy restricting the faculty’s freedom to testify for plaintiffs — raising the possibility that Dr. Gilstrap is biased. Thus, the Walkers are not engaged in global discovery of the type disapproved in Russell; rather, they narrowly seek information regarding the potential bias suggested by the witness’ own deposition testimony and that of his professional colleague.
Our rules of civil procedure, and the federal rules upon which they are based, mandate a flexible approach to discovery. A party may seek any information which “appears reasonably calculated to lead to the [839]*839discovery of admissible evidence.” Tex. R.Civ.P. 166b(2)(a). Evidence of bias of a witness is relevant and admissible. See Tex.R.Civ.Evid. 613(b).5
The trial court erred in failing to apply the foregoing rules to determine whether the documents were discoverable. Instead, the trial court simply read Russell as an absolute bar to discovery, even though the circumstances here are quite distinguishable. In so doing, the trial court misapplied the Russell holding. We expressly disapprove such a mechanical approach to discovery rulings.6
Having concluded that the trial court erred in denying the discovery based solely on Russell, we now must determine whether the appropriate remedy lies by writ of mandamus. “Mandamus issues only to correct a clear abuse of discretion or the violation of a duty imposed by law when there is no other adequate remedy by law.” Johnson v. Fourth Court of Appeals, 700 S.W.2d 916, 917 (Tex.1985).7 We therefore examine whether the trial court’s error in the present case constituted a clear abuse of discretion and, if so, whether there is an adequate remedy by appeal.
1. Clear Abuse of Discretion
Traditionally, the writ of mandamus issued only to compel the performance of a ministerial act or duty. See Wortham v. Walker, 133 Tex. 255, 277, 128 S.W.2d 1138, 1150 (1939); Arberry v. Beavers, 6 Tex. 457 (1851); Helen A. Cassidy, The Instant Freeze-Dried Guide to Mandamus Procedure in Texas Courts, 31. S.Tex. L.Rev. 509, 510 (1990); Comment, The Expanding Use of Mandamus to Review Texas District Court Discovery Orders: An Immediate Appeal Is Available, 32 Sw. L.J. 1283, 1288 (1979).
Since the 1950’s, however, this Court has used the writ to correct a “clear abuse of discretion” committed by the trial court. See, e.g., Joachim v. Chambers, 815 S.W.2d 234, 237 (Tex.1991); Jampole v. Touchy, 673 S.W.2d 569, 574 (Tex.1984); West v. Solito, 563 S.W.2d 240, 244 (Tex.1978); Womack v. Berry, 156 Tex. 44, 50, 291 S.W.2d 677, 682 (1956). See generally, David W. Holman & Byron C. Keeling, Entering the Thicket? Mandamus Review of Texas District Court Witness Disclosure Orders, 23 St. Mary’s L.J. 365, 390 (1991); Cassidy, 31 S.Tex.L.Rev. at 510; Note, The Use of Mandamus to Review Discovery Orders in Texas: An Extraordinary Remedy, 1 Rev.Litig. 325, 326-27 (1981); Comment, 32 Sw.L.J. at 1290.
A trial court clearly abuses its discretion if “it reaches a decision so arbitrary and unreasonable as to amount to a clear and prejudicial error of law.” Johnson v. Fourth Court of Appeals, 700 S.W.2d at 917. This standard, however, has different applications in different circumstances.
With respect to resolution of factual issues or matters committed to the trial court’s discretion, for example, the reviewing court may not substitute its judgment for that of the trial court. See Flores v. Fourth Court of Appeals, 777 S.W.2d 38, 41-42 (Tex.1989) (holding that determina[840]*840tion of discoverability under Tex.R.Civ.P. 166b(3)(d) was within discretion of trial court); Johnson, 700 S.W.2d at 918 (holding that trial court was within discretion in granting a new trial “in the interest of justice and fairness”). The relator must establish that the trial court could reasonably have reached only one decision. Id. at 917. Even if the reviewing court would have decided the issue differently, it cannot disturb the trial court’s decision unless it is shown to be arbitrary and unreasonable. Johnson, 700 S.W.2d at 918.
On the other hand, review of a trial court’s determination of the legal principles controlling its ruling is much less deferential. A trial court has no “discretion” in determining what the law is or applying the law to the facts. Thus, a clear failure by the trial court to analyze or apply the law correctly will constitute an abuse of discretion, and may result in appellate reversal by extraordinary writ. See Joachim v. Chambers, 815 S.W.2d 234, 240 (Tex.1991) (trial court abused discretion by misinterpreting Code of Judicial Conduct); NCNB Texas National Bank v. Coker, 765 S.W.2d 398, 400 (Tex.1989) (trial court abused discretion by failing to apply proper legal standard to motion to disqualify counsel); Eanes ISD v. Logue, 712 S.W.2d 741, 742 (Tex.1986) (trial court abused discretion by erroneously finding constitutional violation).
In determining whether the trial court abused its discretion in the present case, we treat the trial court’s erroneous denial of the requested discovery on the sole basis of Russell as a legal conclusion to be reviewed with limited deference to the trial court. This is consistent with our approach in previous mandamus proceedings arising out of the trial court’s interpretation of legal rules. Cf. Axelson, Inc. v. Mcllhany, 798 S.W.2d 550, 555 (Tex. 1990); Barnes v. Whittigton, 751 S.W.2d 493, 495-96 (Tex.1988); Terry v. Lawrence, 700 S.W.2d 912, 913-14 (Tex.1985). Under this analysis, the trial court’s erroneous interpretation of the law constitutes a clear abuse of discretion.
2. Adequate Remedy by Appeal
In order to determine whether the writ should issue, however, we must further decide whether the Walkers have an adequate remedy by appeal.
Mandamus will not issue where there is “a clear and adequate remedy at law, such as a normal appeal.” State v. Walker, 679 S.W.2d 484, 485 (Tex.1984). Mandamus is intended to be an extraordinary remedy, available only in limited circumstances. The writ will issue “only in situations involving manifest and urgent necessity and not for grievances that may be addressed by other remedies.” Holloway v. Fifth Court of Appeals, 767 S.W.2d 680, 684 (Tex.1989) (quoting James Sales, Original Jurisdiction of the Supreme Court and the Courts of Civil Appeals of Texas in Appellate Procedure in Texas, § 1.4[l][b] at 47 (2d ed. 1979)). The requirement that persons seeking mandamus relief establish the lack of an adequate appellate remedy is a “fundamental tenet” of mandamus practice. Holloway, 767 S.W.2d at 684.
Our requirement that mandamus will not issue where there is an adequate remedy by appeal is well-settled.8 On a few occasions, however, we have not fo[841]*841cused on this requirement when applying mandamus review of discovery orders. For example, in Barker v. Dunham, 551 S.W.2d 41 (Tex.1977), the trial court refused to compel defendant’s representative to answer certain deposition questions, and the plaintiff applied to this Court for a writ of mandamus. We concluded that the trial court had abused its discretion, and ordered that the writ conditionally issue. We never discussed the well-settled requirement of inadequate remedy by appeal.
A few months later, in Allen v. Hum-phreys, 559 S.W.2d 798 (Tex.1977), the Court again conditionally issued a writ of mandamus to correct a discovery abuse without considering whether the relator had an adequate remedy by appeal. The real party in interest in Allen raised this argument, but the Court avoided the issue by citing Barker. Id. at 801.
Commentators quickly criticized the Barker and Allen opinions. See James Sales, Pre-Trial Discovery in Texas, 31 Sw.L.J. 1017, 1033 (1977); Comment, The Expanding Use of Mandamus to Review Texas District Court Discovery Orders: An Immediate Appeal Is Available, 32 Sw.L.J. 1283, 1300 (1979) (In most cases “forcing a party to await the completion of the trial in order to seek appellate review will not endanger his substantial rights....”); Note, Mandamus May Issue To Compel A District Judge to Order Discovery, 9 Tex.Tech L.Rev. 782 (1978) (mandamus should not be a substitute for appeal).
In Jampole v. Touchy, 673 S.W.2d 569 (Tex.1984), the Court again used the extraordinary writ of mandamus to compel discovery which had been denied by the trial court. Unlike in Barker and Allen, however, the Court in Jampole addressed whether relator had an adequate appellate remedy. The underlying suit in Jampole was a products liability action, and the disputed discovery materials included alternate design and assembly documents. The Court held that relator did not have an adequate remedy by appeal because denial of this discovery effectively prevented relator from proving the material allegations of his lawsuit. 673 S.W.2d at 576. Remedy by appeal in a discovery mandamus is not adequate where a party is required “to try his lawsuit, debilitated by the denial of proper discovery, only to have that lawsuit rendered a certain nullity on appeal....” Id.
Although the Court in Jampole recognized the need to address whether relator had an adequate remedy by appeal, it expressly refused to overrule Barker and Allen. Id. Perhaps because of this, we have on several occasions since Jampole used mandamus to correct discovery errors without considering whether the relator had an adequate appellate remedy. See Loftin v. Martin, 776 S.W.2d 145 (Tex.1989); Barnes v. Whittington, 751 S.W.2d 493 (Tex.1988); Lunsford v. Morris, 746 S.W.2d 471 (Tex.1988); Turbodyne Corp. v. Heard, 720 S.W.2d 802 (Tex.1986); Terry v. Lawrence, 700 S.W.2d 912 (Tex.1985); Lindsay v. O’Neill, 689 S.W.2d 400 (Tex.1985).
On many other occasions, however, we have still required a showing of inadequate [842]*842remedy by appeal in mandamus proceedings involving other types of pre-trial orders, even those involving discovery. See, e.g., TransAmerican Natural Gas Corp. v. Powell, 811 S.W.2d 913, 919 (Tex.1991); Hooks v. Fourth Court of Appeals, 808 S.W.2d 56, 59-60 (Tex.1991); Bell Helicopter Textron, Inc., v. Walker, 787 S.W.2d 954, 955 (Tex.1990); Stringer v. Eleventh Court of Appeals, 720 S.W.2d 801, 801-02 (Tex.1986). In Hooks, for example, we reaffirmed that the “cost or delay of having to go through trial and the appellate process does not make the remedy at law inadequate.” 808 S.W.2d at 60.
The requirement that mandamus issue only where there is no adequate remedy by appeal is sound, and we reaffirm it today. No mandamus case has ever expressly rejected this requirement, or offered any explanation as to why mandamus review of discovery orders should be exempt from this “fundamental tenet” of mandamus practice. Without this limitation, appellate courts would “embroil themselves unnecessarily in incidental pre-trial rulings of the trial courts” and mandamus “would soon cease to be an extraordinary writ.” Braden v. Downey, 811 S.W.2d 922, 928 (Tex.1991). We thus hold that a party seeking review of a discovery order by mandamus must demonstrate that the remedy offered by an ordinary appeal is inadequate. We disapprove of Barker, Allen, and any other authorities to the extent they might be read as abolishing or relaxing this rule.
We further hold that an appellate remedy is not inadequate merely because it may involve more expense or delay than obtaining an extraordinary writ. As we observed in Iley v. Hughes, the “delay in getting questions decided through the appellate process ... will not justify intervention by appellate courts through the extraordinary writ of mandamus. Interference is justified only when parties stand to lose their substantial rights.” 158 Tex. at 368, 311 S.W.2d at 652.
On some occasions, this Court has used, or at least mentioned, the more lenient standard first articulated in Cleveland v. Ward, 116 Tex. 1, 14, 285 S.W. 1063, 1068 (Tex.1926), that the remedy by appeal must be “equally convenient, beneficial, and effective as mandamus.” See, e.g., Jampole v. Touchy, 673 S.W.2d 569, 576 (Tex.1984); Crane v. Tunks, 160 Tex. 182, 190, 328 S.W.2d 434, 439 (Tex.1959). This standard, literally applied, would justify mandamus review whenever an appeal would arguably involve more cost or delay than mandamus. This is unworkable, both for individual cases and for the system as a whole. Mandamus disrupts the trial proceedings, forcing the parties to address in an appellate court issues that otherwise might have been resolved as discovery progressed and the evidence was developed at trial. Moreover, the delays and expense of mandamus proceedings may be substantial. This proceeding, for example, involving rulings on collateral discovery matters, has delayed the trial on the merits for over two years. The impact on the appellate courts must also be considered. We stated in Braden that “[t]he judicial system cannot afford immediate review of every discovery sanction.” 811 S.W.2d 922, 928. It follows that the system cannot afford immediate review of every discovery order in general.9 We therefore disapprove of Cleveland, Crane, Jampole and any other authorities to the extent that they imply that a remedy by appeal is inadequate merely because it might involve more delay or cost than mandamus.
Justice Doggett’s dissent argues that because discovery errors often constitute harmless errors under Tex.R.App.P. 81(b)(1), parties denied mandamus relief will be deprived of any remedy since the [843]*843error will not provide a basis for appellate reversal. This is nothing more than a thinly disguised attack on the harmless error rule. Avoiding interlocutory appellate review of errors that, in the final analysis, will prove to be harmless, is one of the principal reasons that mandamus should be restricted.
Justice Doggett’s dissent also suggests that we will be unable to develop a coherent body of discovery law without unrestricted mandamus review. We do not think, however, that losing parties will be reluctant to raise perceived discovery errors on appeal, nor will an appellate court be foreclosed from writing on discovery issues, even when the error may be harmless. See, e.g., Lovelace v. Sabine Consolidated, Inc., 733 S.W.2d 648, 652-53 (Tex.App.—Houston [14th Dist.] 1987, writ denied).
Nor are we impressed with the dissenters’ claim that strict adherence to traditional mandamus standards will signal an end to effective interlocutory review for some parties or classes of litigants. There are many situations where a party will not have an adequate appellate remedy from a clearly erroneous ruling, and appellate courts will continue to issue the extraordinary writ. In the discovery context alone, at least three come to mind.
First, a party will not have an adequate remedy by appeal when the appellate court would not be able to cure the trial court’s discovery error. This occurs when the trial court erroneously orders the disclosure of privileged information which will materially affect the rights of the aggrieved party, such as documents covered by the attorney-client privilege, West v. Solito, 563 S.W.2d 240 (Tex.1978), or trade secrets without adequate protections to maintain the confidentiality of the information. Automatic Drilling Machines v. Miller, 515 S.W.2d 256 (Tex.1974). As we noted in Crane: “After the [privileged documents] had been inspected, examined and reproduced ... a holding that the court had erroneously issued the order would be of small comfort to relators in protecting their papers.” 160 Tex. at 190, 328 S.W.2d at 439. It may also occur where a discovery order compels the production of patently irrelevant or duplicative documents, such that it clearly constitutes harassment or imposes a burden on the producing party far out of proportion to any benefit that may obtain to the requesting party. See, e.g., Sears, Roebuck & Co. v. Ramirez, 824 S.W.2d 558, 35 Tex.Sup.Ct.J. 454 (1992) (demand for tax returns); General Motors Corp. v. Lawrence, 651 S.W.2d 732 (Tex.1983) (demand for information about all vehicles for all years).
Second, an appeal will not be an adequate remedy where the party’s ability to present a viable claim or defense at trial is vitiated or severely compromised by the trial court’s discovery error. It is not enough to show merely the delay, inconvenience or expense of an appeal. Rather, the relator must establish the effective denial of a reasonable opportunity to develop the merits of his or her case, so that the trial would be a waste of judicial resources. We recently held that when a trial court imposes discovery sanctions which have the effect of precluding a decisión on the merits of a party’s claims — such as by striking pleadings, dismissing an action, or rendering default judgment — a party’s remedy by eventual appeal is inadequate, unless the sanctions are imposed simultaneously with the rendition of a final, appealable judgment. TransAmerican Natural Gas Corp. v. Powell, 811 S.W.2d 913, 919 (Tex.1991). Similarly, a denial of discovery going to the heart of a party’s case may render the appellate remedy inadequate.
Finally, the remedy by appeal may be inadequate where the trial court disallows discovery and the missing discovery cannot be made part of the appellate record, or the trial court after proper request refuses to make it part of the record, and the reviewing court is unable to evaluate the effect of the trial court’s error [844]*844on the record before it. See Tom L. Scott, Inc. v. McIlhany, 798 S.W.2d 556, 558 (Tex.1990) (“[MJandamus is the only remedy because the protective order shields the witnesses from deposition and thereby prevents the evidence from being part of the record.”); see generally Jampole, 673 S.W.2d at 576 (“Because the evidence exempted from discovery would not appear in the record, the appellate courts would find it impossible to determine whether denying the discovery was harmful.”). If the procedures of Tex.R.Civ.P. 166b(4) are followed, this situation should only rarely arise. If and when it does, however, the court must carefully consider all relevant circumstances, such as the claims and defenses asserted, the type of discovery sought, what it is intended to prove, and the presence or lack of other discovery, to determine whether mandamus is appropriate.10
In the present case, the Walkers seek documents from the Center to impeach one defendant’s expert witness. This information is not privileged, burdensome or harassing, nor does it vitiate or severely compromise the Walkers’ ability to present a viable claim. In fact, as we have already noted, the trial court may ultimately conclude that it is not admissible or even discoverable. Finally, although the materials are not before us, they were considered below, and we know of no reason why they would not be available on appeal. Therefore, under our traditional standards of mandamus review, as measured by the factors we mention above, the Walkers have an adequate remedy by appeal and mandamus is inappropriate.
For the above reasons, we conclude that the Walkers have not established their right to relief by mandamus on either discovery matter. Therefore, we deny the Walkers' petition for writ of mandamus.
GONZALEZ, J., concurs and files an opinion.
DOGGETT, J., dissents and files an opinion, joined by MAUZY, J.
GAMMAGE, J., dissents and files an opinion.