Petitioner, who is the defendant in an action pending before the Superior Court of Sacramento County entitled Babcock v. McClatchy Newspapers, a corporation et al., seeks a writ of mandate directing respondent court to set aside orders discharging an order to show cause why the plaintiff in that action should not be compelled to answer certain questions and complete his deposition, denying petitioner’s motion for an inspection of documents under the control of the plaintiff, and quashing and recalling subpoenas duces tecum served on witnesses who are not parties to the action. Petitioner further seeks to compel respondent court to permit the taking or completion of depositions and the making of an inspection.
In January, 1943, Otis D. Babcock, who will be referred to hereinafter as plaintiff, commenced an action in respondent court against McClatchy Newspapers, hereinafter referred to as defendant, and A. J. Harder, an attorney, for damages for alleged libel. The complaint averred that on August 8, 1942, when plaintiff was District Attorney of Sacramento County and a candidate for re-election, defendant published an article in the “Sacramento Bee” containing the following defamatory matter: ‘' How was it possible for you, Mr. Babcock, going into office dead broke, on a salary of $4,500, to buy an office building at a purported price of $80,000 ? ... In contrast to the record of the incumbent Babcock, John Quincy Brown . . . has an exemplary record, both as a member of the bar and in his private life. Sacramento County needs this man.” It was further alleged that the article was false; that in publishing the same defendant acted maliciously and with intent and design to injure, disgrace and defame plaintiff; and that defendant intended thereby to be understood, and was understood by readers of the publication, as asserting that plaintiff was a dishonest public official and guilty of corruption in office.
Defendant filed an answer admitting publication of an article which included the passage above quoted and denying the other material averments of the complaint. The answer also contained pleas of privilege, mitigating circumstances and truth or justification. In support of the claim of privi*390lege, defendant alleged that the article containing the asserted libelous matter was a fair report of a challenge issued by Harder to plaintiff to debate publicly certain questions relating to plaintiff’s fitness for office; that the article constituted merely a reiteration of a news item previously published in another newspaper of general circulation; that the nature and source of the assets of a public official are proper matters of newspaper comment during a campaign wherein such official seeks re-election; and that the material contained in the article was of interest to the public and was published for public benefit.
As mitigating circumstances, it was alleged that at the time of publication defendant believed with good cause that plaintiff had accumulated property during his term of office not to be accounted for by his salary, and that, to defendant’s knowledge, he had purchased an office building at a purported price of $80,000. The plea of justification rested upon allegations to the effect that the statements were true in that during his term of office plaintiff increased his net worth to an extent not reasonably to be accounted for by his salary and that he increased his assets by engaging in private business, including the buying and selling of real estate on a large scale, in violation of section 78 of the county charter which prohibits elective officers from engaging in any private practice or business.
Plaintiff’s deposition was originally taken by defendant before an answer was filed in the case. He was questioned generally as to his financial status and transactions while district attorney, and he agreed to allow defendant to examine certain records relating thereto. In reliance upon plaintiff’s offer, defendant did not complete its interrogation of the witness, but before the records were examined plaintiff withdrew his consent. The day after defendant filed its answer, it gave notice of the taking of the depositions of named officials of banks, title companies, and brokerage firms. Subpoenas duces tecum were issued directing the witnesses to produce records of plaintiff’s bank deposits and withdrawals, loans to and financial statements from him, securities bought and sold by him, and real estate transactions handled for him during the period of his incumbency as district attorney. On the same day, defendant filed and served notice of motion for inspection of records and documents under plaintiff’s control, including state and federal *391income tax returns during the years he was district attorney, records of his bank deposits and withdrawals as well as of loans procured from and financial statements supplied to named banks during that period, records of his purchases and sales of real estate for the same period, and records of his brokerage account.
Shortly after the filing of the notices, plaintiff demurred to the answer and noticed a motion to quash the subpoenas duces tecum on the ground that they were unreasonable and oppressive in that the issues in the case had not been defined, and that the supporting affidavits failed to disclose the contents of the papers sought to be produced or their materiality and relevancy to the issues. The demurrer to the pleas of mitigation and justification was sustained, and orders were made quashing and recalling the subpoenas duces tecum and denying the motion for inspection.
Defendant thereafter amended its answer. In its defense of mitigation it alleged that at the time of the supposed libel it had knowledge that plaintiff had publicly announced, prior to his election, that he was a “poor man”; that it was aware he had been buying many parcels of realty during his term of office, including an office building in Sacramento; that the purchase of the building at a price of $80,000 had been widely publicized; that defendant therefore believed that plaintiff had gone into office “dead broke”; that plaintiff purchased many properties, including the office building, during his incumbency, and that the public had a right to know these facts and to have an explanation by plaintiff as to the source of his assets; that the publication was without malice; and that defendant did not thereby mean to be understood as asserting that plaintiff was a dishonest public official or guilty of corruption in office.
In support of its defense of justification defendant alleged on information and belief that the factual statement underlying the purported libel was true in that plaintiff had increased his net worth more than $80,000 during his term of office; that he was worth approximately $20,000 when he became district attorney; that after taking office he accumulated property with the result that his net worth exceeded $100,000 at the time of the alleged libel; that he received no property during his term of office by gift, devise, bequest or inheritance; that he was prohibited by law from engaging in private, practice or business during his incumbency; and *392that the increase in his net worth did not result from his ownership of property acquired before the commencement of his term nor from the receipt of his salary as district attorney. A general demurrer was overruled as to the amended plea of mitigation, but was sustained without leave to amend as to the amended plea of justification.
Thereafter, the court made an order permitting defendant to reopen plaintiff’s deposition. Plaintiff refused to answer questions pertaining to the preparation, filing, availability, and contents of income tax returns, the source of income shown therein, and the purchase of real property, including the source and amount of the purchase price thereof. Counsel for defendant stated that he desired to interrogate plaintiff to ascertain the extent to which and the means by which his net worth and income increased after he became district attorney; that defendant intended to show that plaintiff made over $80,000 while district attorney, that his real estate transactions were so great as to constitute doing business in violation of the charter provisions, and that he had practiced law during his incumbency. Plaintiff declined to answer such questions on the ground that they were incompetent, irrelevant, immaterial and without the issues. Application was therefore made by defendant for an order directing him to show cause why he should not be compelled to answer the questions propounded and complete his deposition. Respondent court, sustaining plaintiff’s objections, in effect discharged the order to show cause and ruled that plaintiff would be required to answer only the questions directed to whether he purchased designated parcels of realty, that he would not be required to answer the remaining queries, and that defendant would not be permitted to question him along the lines indicated. The present proceeding was then commenced.
Mandamus is the appropriate remedy to secure the enforcement of a litigant’s statutory right to take depositions, and an appeal from a final judgment is neither speedy nor adequate where a trial court improperly refuses to order that a deposition be taken. (Christ v. Superior Court, 211 Cal. 593 [296 P. 612]; San Francisco Gas & Electric Co. v. Superior Court, 155 Cal. 30 [99 P. 359, 17 Ann.Cas. 933]; Crocker v. Conrey, 140 Cal. 213 [73 P. 1006]; see Hays v. Superior Court, 16 Cal.2d 260, 265 [105 P.2d 975].) It is contended, however, that the writ lies only where the trial court fails to exercise its authority, as where it refuses to *393issue a commission to take a deposition, and that the writ cannot issue in a proceeding such as this, because the trial court merely acted in a matter within its discretion. Ordinarily the trial court has no discretion to refuse to exercise its powers so far as necessary to secure to a litigant the right to a deposition in the cases defined by the code. (Crocker v. Convey, 140 Cal. 213, 218 [73 P. 1006]; Moran v, Superior Court, 38 Cal.App.2d 328, 334 [100 P.2d 1096]; Scott v. Shields, 8 Cal.App. 12, 16 [96 P. 385]; cf. Christ v. Superior Court, 211 Cal. 593, 601 [296 P. 612].) The language of section 2021 of the Code of CíyíI Procedure providing that “The testimony of a witness . . . may be taken by deposition” confers upon litigants the right to take depositions. (See Hays v. Superior Court, 16 Cal.2d 260, 264 [105 P.2d 975].) It is true that in the Hays case this court held that the trial court could, in its discretion, defer the taking of a deposition until the determination of a pending appeal of the cause in which the deposition was to be used, and, similarly, in Patrick Farms, Inc. v. Superior Court, 13 Cal.App.2d 424 [56 P.2d 1283], it was held proper to continue the taking until it was determined in another action then pending whether plaintiff had the right to maintain the action in which the deposition was sought. It was pointed out in the Hays case, however, that “If . . . the trial court acts . . . in such manner as to deny the right rather than to exercise merely a reasonable control over the exercise of the right, ... its actions would be controlled by mandamus or other appropriate remedy.” (16 Cal.2d at p. 265.) The case now before ns illustrates this distinction. There is a difference between a deferment of the right or conditional refusal to compel a witness to give a deposition and the unreserved refusal to compel a witness to complete his deposition or answer proper questions on the taking thereof. Here the court was passing upon the materiality and relevancy of the questions contained in the deposition, and its ruling, if improper, would in effect require defendant to proceed to trial without the benefits afforded by the deposition to which it is entitled under the code. This does not involve a matter within the discretionary powers of the trial court but, rather, the enforcement of a legal right of a party to the action. Although in the Hays and Patrick Farms eases the deferment of the time of taking the deposition was deemed justified by reason of special cir*394cumstances, there is no suggestion in those eases that it would be proper to compel a party to proceed to trial without a deposition for which a proper request had been made.
By refusing to compel a witness to answer proper questions, a trial court may effectively deny a litigant the right to take a deposition, since a right without means of enforcement, if such can exist, is of little practical value. Consequently, trial courts have been directed by writ of mandate to compel witnesses to answer questions on the taking of their depositions on the theory that it is their judicial duty to secure to a party the means of obtaining in advance of the trial information concerning the issues and the means of producing at the trial the evidence necessary to sustain his action or defense. (Crocker v. Conrey, 140 Cal. 213 [73 P. 1006]; Wissman v. Cabaniss, 34 Cal.App. 487 [168 P. 150] ; Johnston v. St. Sure, 50 Cal.App. 735 [195 P. 947]; Scott v. Shields, 8 Cal.App. 12 [96 P. 385].)
It is argued that if mandamus will lie whenever a court refuses to direct a witness to answer a question, the trial of actions will be delayed and the appellate courts will be deluged with petitions. In this case, however, it was stipulated on submission of the order to show cause that any questions similar to those asked of plaintiff “or along the line indicated by defendant’s counsel” would be objected to by plaintiff and that the witness would decline to answer. The defendant is thus attempting to enforce its right to question plaintiff along the general lines indicated in the stipulation and, as will more clearly appear hereafter, the problem presented is not limited to the materiality of specific questions but involves the determination of the permissive scope of examination upon the taking of a deposition.
The respondent court declined to compel plaintiff to answer the questions upon the ground that they were directed to defenses which had been eliminated by the ruling on demurrer, and that therefore the answers would be incompetent and immaterial as not within the issues. While the order on demurrer ruled out certain issues for the time being, the status of the pleadings as so limited is.not the-exclusive measure of the scope of inquiry on deposition. Different principles govern the determination of the materiality of evidence sought to be obtained by means of depositions and the admissibility of evidence offered upon the trial. The relevancy of evidence on the taking of a deposition is to be *395determined by the subject matter of the action and by the potential as well as actual issues in the case. (Code Civ. Proc., §§ 2065, 2066; San Francisco Gas & Electric Co. v. Superior Court, 155 Cal. 30 [99 P. 359, 17 Ann.Cas. 933]; Most v. Superior Court, 25 Cal.App.2d 394 [77 P.2d 532]; Rossbach v. Superior Court, 43 Cal.App. 729 [185 P.879]; Kibele v. Superior Court, 17 Cal.App. 720 [121 P. 412]; see 26 C.J.S. 815, 886.) In San Francisco Gas & Electric Co. v. Superior Court, supra, where defendant sought to take the deposition of a witness while the case was pending on appeal, this court said: “As soon as the summons has been served either party may commence the taking of depositions relevant to any possible issue that may arise upon a denial of the allegations of the complaint or upon the allegation of new matter in the answer . . . the real question is not whether . . . testimony would be material to the issues which were tried, but whether it will be material on a new trial, and under such an amendment to the answer as the circumstances of the case would warrant the court in allowing.” (155 Cal. at pp. 34, 39.) And in Rossbach v. Superior Court, supra, where plaintiff sought to take the deposition of the defendant after a general demurrer to the complaint had been sustained, the court stated that “plaintiff’s right to have defendant’s deposition depends not alone upon whether it is material to issues tendered [by the complaint] but the right thereto is equally clear if it would be material to any possible issue raised by new allegations contained in an amended complaint which the court might properly permit plaintiff to file.” (43 Cal. App. at p. 731.)
The fact that the ruling on demurrer eliminated the issues embraced by the deposition does not prevent such issues from being classed as potential. The sustaining of a demurrer relates only to the issues raised by the pleadings as they exist at the time of the ruling on the demurrer. A trial court may nevertheless properly permit an amendment to the pleadings during the course of trial; it may reconsider its ruling during trial; or the ruling may be reversed upon appeal. Thus if, in the present case, evidence of plaintiff’s financial transactions would be relevant to such potential issues, defendant would be entitled to take his deposition along the lines suggested.
The questions that plaintiff refused to answer related *396to the extent and means by which his net worth and income increased, if at all, after he became district attorney. Although these matters may not be relevant under the pleadings as limited by the ruling on demurrer, they clearly are relevant to possible or potential issues which might properly be raised during the course of this action. For example, the truth or falsity of the alleged libel is an actual or potential issue, which directly or indirectly involves the sources of plaintiff’s income during his term of office. Since the evidence that defendant sought to obtain by the deposition related to actual or potential issues, it is relevant, and defendant is entitled to complete the taking of the deposition.
The next question is whether the defendant has made a sufficient showing in support of its motion for an order of inspection of plaintiff’s papers relating to his transactions with banks and his dealings in real estate and securities. Plaintiff makes the familiar contention that the object is a mere “fishing expedition” through his private papers, in violation of the constitutional guaranty against unreasonable searches and seizures, and claims that the affidavit is too general and does not state positively or with particularity what documents are sought or what facts each paper will establish.
The right to have an inspection of papers and documents in the hands of a party to the action or a third person is governed by different rules from those applying to depositions. A party or witness has a constitutional right to be free from unreasonable searches and seizures, and it is therefore incumbent upon the one seeking an inspection to show clearly that he has a right thereto and that the constitutional guaranties will not be infringed. Hence, the affidavit in support of the demand for inspection must identify the desired books, papers and documents and it must clearly show that they contain competent and admissible evidence which is material to the issues to be tried. The affiant cannot rely merely upon the legal conclusion, stated in general terms, that the desired documentary evidence is relevant and material.
Petitioner contends that under the decision in Union Trust Co. v. Superior Court, 11 Cal.2d 449 [81 P.2d 150, 118 A.L.R. 259], these rules must be liberally applied and that it has met the requirements there imposed. In that case after an exhaustive examination of the history and development of discovery, the court stated that “the trend of judicial *397decisions is to relax the rules which relate to the taking of evidence by ancillary proceedings, of which the inspection of. documents is one method, to the end that the trial of actions may be expedited and justice be more efficaciously and speedily administered.” (11 Cal.2d at p. 462.) The relaxation of the rule, however, does not mean an abolition of the requirements that the papers be identified and that they be shown to be relevant and material. The theory is that the statutory proceeding of inspection is remedial in character, and that the right of inspection should be encouraged as an aid to the proof of issues before the court. Accordingly, if it is shown that the documents contain material evidence, it is sufficient if they are identified by a description that can be reasonably understood by the adverse party. While the Union Trust Company case related to an action arising out of an alleged violation of duty under an express trust, the existence of a fiduciary relationship was only one factor considered by the court in reaching its conclusion and, as pointed out by defendant, the opinion supports a liberal application of the rule irrespective of the relationship of the parties. The affidavit therein incorporated by reference certain allegations of the pleadings from which it was apparent that evidence in the described records was material. In the present case the defendant has not brought itself within the rule for it has not alleged sufficient facts to show the materiality of the desired evidence.
In considering the sufficiency of the showing in support of the demand for inspection, we will assume, without so deciding, that the defenses of justification, mitigation and privilege have been adequately pleaded. The affidavit avers that plaintiff had certain business and financial transactions with various banks, that he bought and sold securities through a stockbroker, that he engaged in various real estate transactions and that he made state and federal income tax returns. The affidavit does not specify or particularly describe any papers or documents involving those transactions, but merely states, as to each type of document, the general conclusion that “the matters” or “the records and transactions” in question “are relevant and material in the above entitled action and to the issues therein and the defense thereof.” Nowhere in the affidavit is there any more specific averment as to the contents of any one or more of those papers and *398documents, or as to what facts, if any, would or could be proved thereby.
It appears to be defendant’s theory that plaintiff made profits and increased his assets during his term of office by means of private practice and business transactions in which he was prohibited from engaging by the terms of the county charter, and that these facts will appear from an examination of the records and documents in question. It may be admitted that, if such is the case, then some of the records and documents would probably show those ultimate facts, but it cannot be said that they must necessarily show such facts or any of them, nor can it be said, on the basis of defendant’s affidavit, that their relevancy and materiality clearly appear. Although it would be unjust to permit plaintiff to recover for an alleged libel by suppressing or withholding evidence which is material or vital to the action, defendant must first show the materiality of the desired evidence and cannot obtain permission to search through all of plaintiff’s papers and records merely in the hope or expectation that the investigation will disclose favorable information.
Compliance with the rule requires more explicit averments in the affidavit than are present here, and may involve information which defendant does not now have, but it is not thereby deprived of the right or ability to defend, since it is entitled, before going to trial, to complete plaintiff’s deposition. If the defendant, on deposition, is accorded its right to examine plaintiff as to the identity and contents of the papers and documents pertaining to the defenses of justification, mitigation and privilege, it may thereby secure the necessary information for use in making an affidavit which will disclose to the court the identity of the desired evidence and its materiality and relevancy to the issues presented in the libel action.
What has been said applies with equal force to defendant’s attempt, by supoena duces tecum, to inspect papers and documents in the hands of third parties. The affidavit does not specifically describe any papers or documents, or their contents, but merely refers to various financial and business transactions, and avers generally that the records thereof, in the hands of the respective witnesses, are relevant and material.
It follows that defendant is not entitled, on the present showing, to compel an inspection of documents in the hands *399of plaintiff or the third parties, but it is entitled to a writ of mandate directing respondent to set aside its orders preventing the completion of plaintiff’s deposition and to make the necessary orders to effectuate those proceedings in accordance with the views expressed in this opinion. Let the writ issue accordingly.
Shenk, J., Edmonds, J., Traynor, J., Sehauer, J., and Spence, J., concurred.