This is an original mandamus proceeding instituted by Jessie B. Loftin, relator, against respondent, Honorable John Martin, Judge of the Second 9th Judicial District Court of Polk County, Texas.1 Rela*146tor seeks a writ of mandamus directing Judge Martin to rescind his order of May 10, 1988 and further directing respondent to allow relator to obtain various reports and documents made during the investigation of relator’s underlying claim.
The real party in interest, Lumbermens Mutual Casualty Company (Lumbermens), filed suit to set aside an award of the Texas Industrial Accident Board granted to relator, Jessie Loftin. Loftin then brought a counterclaim for an affirmative award of total and permanent incapacity and requested Lumbermens to produce certain documents. Lumbermens filed its objections to three particular requests for production [Request # 2, # 3 and # 4], and a hearing was thereafter set on these discovery matters for February 9, 1988. Although counsel for Lumbermens appeared at the discovery hearing, neither Loftin nor his attorney appeared nor did either notify the court of any reason for their non-attendance. On May 10, 1988, Judge Martin signed an order sustaining Lumbermens’ objections to the three requests for production.
Loftin then filed a mandamus petition in the Ninth Court of Appeals seeking to set aside Judge Martin’s order of May 10. The court of appeals in an unpublished per cu-riam opinion held that because the discovery requests were so overly broad and vague it could not say that the trial court abused its discretion, citing Durham v. Carman Communications, Inc., 645 S.W.2d 845, 848 (Tex.App.—Amarillo 1982, writ dism’d) (the trial court did not abuse its discretion in light of the fact that the disclosure demand was too broad).
In this mandamus proceeding, the true inquiry is whether the trial court abused its discretion in reaching its decision. Our focus remains on the trial court’s order regardless of the court of appeals’ decision. Johnson v. Fourth Court of Appeals, 700 S.W.2d 916, 918 (Tex.1985). Under the facts of this case, the relator must show that the trial court’s action in sustaining Lumbermens’ objections was so arbitrary and unreasonable as to amount to a clear and prejudicial error of law. Id. at 917. King v. Guerra, 1 S.W.2d 873, 376 (Tex.Civ.App.—San Antonio 1927, writ ref’d); Bush v. Vela, 535 S.W.2d 803, 805 (Tex.Civ.App.—Corpus Christi 1976, orig. proceeding). A mere error of judgment is not an abuse of discretion.
We first consider whether Judge Martin abused his discretion in sustaining Lumber-mens’ objection to request for production # 2. Loftin’s request # 2 was as follows:
Request is hereby made that reports be made by all experts you anticipate calling at the trial of this cause to contain all factual observations, tests, supporting data, calculations, photographs and opinions and produced for inspection and copying.
Lumbermens responded as follows:
The request is objected to on the grounds that it constitutes a request that the Counter-Defendant ask expert witnesses to prepare written reports for the benefit of Counter-Plaintiff, which is outside the scope of discovery under Rule 167. Subject to this objection, Counter-Defendant is unable to comply with the request because it has not yet made a decision on what experts, if any, it will call to testify. However, Counter-Defendant may call to testify any of the physicians who have seen and/or examined Counter-Plaintiff for his alleged injuries and copies of all their written reports are already in your possession.
Rule 166b(2)(e) of the Texas Rules of Civil Procedure governs the discoverability of experts and reports of experts. Basically, it provides for the discovery of facts known, mental impressions and experts’ opinions, and the subject matter on which the witness is expected to testify. A request for production of reports of experts, however, must seek an actual document in existence because a party will not be compelled to create or construct it for his opponent. 2 R. McDonald, Texas Civil Practice in District and County Courts, § 10.03 (rev. 1982). The only instance to the con*147trary is found in Tex.R.Civ.P. 166b(2)(e)(4) which provides:
If the discoverable factual observations, tests, supporting data ... of an expert who will be called as a witness have not been recorded and reduced to tangible form, the trial judge may order these matters reduced to tangible form and produced within a reasonable time before the date of trial.
Here, Loftin requested that reports be made by experts, and Lumbermens objected to such request. According to Rule 166b(2)(e)(4), it was incumbent upon Loftin, after Lumbermens objected, to obtain an order from the trial court mandating the creation and production of such reports. No such order has been sought by Loftin nor has such an order been signed by Judge Martin. Accordingly, Loftin’s demand for a report is premature because the report is not in existence.
Loftin’s request for production #2 is further premature because no experts had yet been designated by Lumbermens at the time of the discovery hearing. This factor was brought to the attention of the trial court through Lumbermens’ objection. It was within the trial court’s discretion to disallow the request for production # 2 at least until Lumbermens could designate their experts. According to Rule 166b(2)(e)(3), the trial judge has discretion to compel a party to make the determination and disclosure of whether an expert may be called to testify within a reasonable and specific time before the date of trial.
We therefore hold that Judge Martin was within his discretion in not ordering production of experts’ reports when no experts were designated as of the date of the hearing. Thus, Loftin’s request for production #2 was premature.
The second objection was made to Lof-tin’s request for production # 3 in which he sought production of:
all documents, statements, and communications made during the normal scope of investigating the claimant-employee from July 20, 1986 [date of accident] through the date of the filing of this suit.
Lumbermens objected to this request by asserting the “investigative privilege” of Rule 166b(3) of the Texas Rules of Civil Procedure. Specifically, Lumbermens objected that the documents requested “constitute the internal thought processes and evaluations of [Loftin’s] claims within [Lumbermens’] organization and such matters are not discoverable.” Lumbermens also objected on the ground that the matters requested constitute communications between representatives of Lumbermens that were made after Loftin’s injury and in anticipation of Lumbermens’ defense.
In Peeples v. Fourth Court of Appeals, 701 S.W.2d 635 (Tex.1985), we formulated the procedure to be followed by a party seeking to exclude documents from discovery. Although in Peeples the claim concerned a party’s right to privacy, the same procedure applies to claims of privilege. In Peeples we held that pursuant to Rule 166b(4) of the Texas Rules of Civil Procedure, any party who seeks to exclude documents from discovery must (1) specifically plead the particular privilege or immunity claimed and (2) provide evidence supporting such claim. The trial court must then determine whether an in camera inspection is necessary, and, if so, the party seeking protection must segregate and produce the documents to the court. See Tex.R.Civ.P. 166b(4).
In the present case, Lumbermens specifically pleaded the investigative privilege of Rule 166b(3). However, Lumbermens did not present testimony or evidence at the discovery hearing regarding its claimed privilege. Lumbermens argues, however, that the trial court could merely look at Loftin’s request for production #3 and know that the requested items were privileged.
We are unpersuaded by Lumber-mens’ argument. The investigative privilege of Rule 166b(3) is governed by the rule in Allen v. Humphreys, 559 S.W.2d 798, 802 (Tex.1977); Stringer v. Eleventh Court of Appeals, 720 S.W.2d 801, 802 (Tex.1986). Only information obtained by a party after there is good cause to believe a suit will be filed or after institution of a *148lawsuit is privileged. The burden under Rule 166b(3) is on the party resisting discovery to prove that the evidence is acquired or developed in anticipation of litigation.
Lumbermens produced no evidence to show that the documents requested were prepared in anticipation of litigation. Although Loftin’s request asked for “documents made during the normal scope of investigating the claimant-employee,” we are unable to conclude as a matter of law that such request would involve producing only documents prepared in anticipation of litigation. We recognize the possibility that certain reports or documents could have been formulated after Loftin’s injury which would not be made in anticipation of litigation. The words used in request for production # 3 are not sufficient to support the alleged investigative privilege.
In Weisel Enterprises, Inc. v. Curry, 718 S.W.2d 56, 58 (Tex.1986) this court held that a trial judge who denies discovery in the absence of evidence substantiating the claim of privilege, abuses his discretion. Under the facts of this case, and under the authority of Peeples and Curry, the trial court should have reviewed the allegedly privileged documents in camera. Because there was no evidence of privilege nor an in camera review, we hold that the trial court abused its discretion in denying discovery with respect to Loftin’s request for production #3.
Lumbermens’ final objection was made to Loftin’s request for production # 4 which demanded:
all notes, records, memoranda, documents and communications made that the carrier contends support its allegations [that the award of the Industrial Accident Board was contrary to the undisputed evidence].
Lumbermens objected to request # 4 on the basis that it was so vague, broad and unclear that Lumbermens was unable to determine with reasonable certainty what it was being called upon to produce.
Rule 167 of the Texas Rules of Civil Procedure governs the discovery and production of documents and other tangible things. The 1966 General Commentary to Rule 167, Tex.R.Civ.P. quoted with approval the following from Steely and Gayle, Operation of the Discovery Rules, 2 Houston L.Rev. 222, 223 (1964):
Unlike interrogatories and depositions, Rule 167 is not a fishing rule. It cannot be used simply to explore. You are permitted to fish under deposition procedures, but not under Rule 167. The Motion for Discovery must be specific, must establish materiality, and must recite precisely what is wanted. The Rule does not permit general inspection of the adversary’s records.
Loftin has requested all evidence that supports Lumbermens’ allegations. The request does not identify any particular class or type of documents but it is merely a request that Loftin be allowed to generally peruse all evidence Lumbermens might have. We hold that such request was vague, ambiguous, and overbroad and that the trial court was within its sound discretion in sustaining Lumbermens’ objection. No one seeks to deny Loftin’s right to see evidence against him, but he must formulate his request for production with a certain degree of specificity to allow Lumber-mens to comply.
Because the trial judge abused his discretion in sustaining Lumbermens’ objection to request for production # 3, we conditionally grant Loftin’s petition for writ of mandamus. The writ will issue only if the trial judge refuses to rescind that portion of his order.
HECHT, J., files a dissenting opinion in which PHILLIPS, C.J., and GONZALEZ and COOK, JJ., join.. We acknowledge that the petition for writ of mandamus filed with this court was originally styled: Loftin v. Ninth Court of Appeals. This court on its own motion has changed the re*146spondent from Ninth Court of Appeals to The Honorable John Martin, Judge.