delivered the opinion of the Court.

On April 9, 1959 appellants herein filed an action in claim for wages against the Mayagüez Transport Co., Inc., in the Superior Court, Mayagüez Part. It was alleged in the complaint that about the years 1949 to 1958 plaintiffs rendered services to respondent; that those services were rendered during the legal workday as well as during extra hours in excess of 8 hours per day, 48 hours per week, as well’ as during holidays. It was alleged that for this work they did not receive *261double compensation for the extra hours as provided by § 9 of Act No. 379 of May 15, 1948,1 for works on the basis of unit of work or by the job.

They based their claim on the aforesaid section as well as on the provisions of Mandatory Decree No. 12 of December 4, 1946, as amended on January 8, 1948.2 To institute their claim plaintiffs made use of the procedure established by Act No. 10 of 1917, as amended.3

On May 26, 1959 respondent answered the complaint and served the workers with some interrogatories requesting information on the period during which each one of the plaintiffs worked, “stating the exact dates” .as well as “the number of extra hours of work which they claimed and the specific sum to which each claim amounted.” Plaintiffs did not answer the aforesaid interrogatories and filed a “Motion for the Examination of Payrolls and Interrogatory.” On August 19 the court ordered respondent to place its books and payrolls at the disposal of plaintiffs.

*262In July 1960 the trial judge ordered the dismissal of the case because of inaction. At the request of plaintiffs we granted certiorari, and on May 8, 1961 we vacated the judgment in question, remanding the case for further proceedings.

Plaintiffs then submitted some interrogatories4 and respondent challenged them. The aforesaid challenge was based on the provisions of Rule 30 of the Rules of Civil Procedure *263of 1958,5 and the fact that the information requested was basically the same as that requested by respondent in its interrogatory and that if plaintiffs did not obtain that information notwithstanding the opportunities and the time which was granted them, such negligence should not be remedied by compelling respondent to incur unnecessary expenses and inconveniences to answer the interrogatory.

At the hearing of the motion, plaintiffs alleged that the payroll offered by respondent was “fraudulent” and that the interrogatory submitted by them was aimed at obtaining the necessary information to prepare their case adequately as well as to be able to answer respondent’s interrogatory. The trial judge, by an order of June 9, 1961, granted plaintiffs 30 days in which to answer respondent’s interrogatory. It provided “that once the answer is filed, respondent will be ordered to answer the other one.” They did not do so within the term granted nor appeared at the hearing to try the case on its merits.

On August 8, at respondent’s request, the claim was dismissed. Judgment was rendered accordingly. In order to review this action we issued this writ.

Hence, after our judgment of May 8, 1961, reversing that of the trial court which dismissed the case because of inaction, the respondent court, on June 9, granted plaintiffs 30 days in which to answer the interrogatories submitted by respondent. In spite of the fact that the claimants stated that in order to answer them it was necessary that respondent previously answer the ones formulated by them, the court stated that respondent should answer them after the claimants had answered those of the former. The claimants did *264not answer and they failed to appear on the day set for the hearing of the case on its merits. Then the court dismissed the claim under the authority of the provisions of Rule 34.4 6 of the Rules of Civil Procedure and in § 5 of Act No. 10 of 1917.7

Rule 34.4 as well as Rule 37(d) of 1943, grants discretion to the trial court to dismiss an action if the plaintiff willfully8 fails to serve answers to the interrogatories submitted by the opposite party. Peña v. Heirs of Blondet, 72 P.R.R. 8 (1951); Pepin v. Ready-Mix Concrete, 70 P.R.R. 723 (1950); Craig v. Far West Engineering Company, 265 F.2d 251 (9th Cir. 1959). However, the rule establishes that the failure to serve answers must be willful, that no justification whatsoever exist for failing to do so, General Houses, Inc. v. Marloch Manufacturing Corp., 239 F.2d 510 (2d Cir. 1956); Cardox Corporation v. Olin Mathieson Chemical Corp., 23 F.R.D. 27 (D.C.S.D. Ill. 1958); 4 Moore, Federal Practice *265■§ 37.04 (2d ed.); 2A Barron & Holtzoff § 855 (1961); Developments-Discovery, 74 Harv. L. Rev. 940, 986 (1961), and certainly it can not be stated that in this case plaintiffs had no justification to serve answers to the interrogatories. Respondent had on its records the information which it was requiring from the claimants. We have already seen that in the interrogatories respondent required information on the period during which each one of the complainants worked “stating the exact dates” as well as “the number of extra hours of work which they claimed and the specific sum to which each claim amounted.” The information of the payrolls .and other documents appearing in its records and which the law requires that it keep, could have been easily obtained. It ■seems appropriate to recall what we stated in Sierra, Sec. of Labor v. Superior Court, 81 P.R.R. 540, 548 (1959):

“The courts have often had to face attempts of abuse of discovery of evidence and taking of depositions. For example: in lawsuits involving claims of wages filed in federal courts, defendant employers have required hundreds or thousands of plaintiff employees to answer questions as to their shifts and hours of work, time of employment, earned compensation, specific jobs performed day by day for years, etc. Since the workmen concerned are poorly educated persons, who kept no records, and whose jobs had shifted frequently, the burden caused by such interrogatories was considerable. If to this we add that defendants in those cases had on their records all the information required from the workmen, or could have easily obtained it by properly investigating a few selected employees (as index or test applicable to all the others), it is easy to conclude that such interrogatories were improperly and oppressively used.”

The Legislative Assembly, conscious of the problem which arose from situations like those which we are now considering, and which were the object of our comment in the Sierra ■case, provided the following upon approving the new Act regulating claims of wages:

“In all cases prosecuted under this Act, the Rules of Civil Procedure shall govern insofar as they are not in conflict with *266the specific provisions of this Act or with the summary nature of the procedure hereby established; Provided, in relation with the pre-trial means of disclosure authorized by the Rules of Civil Procedure, that the defendant may not use them to obtain information which must appear in the records, payrolls, wage lists and other records which the employers are bound to keep under the provisions of the Minimum Wage Act and the regulations promulgated thereunder, except any testimony given or document submitted by the complainant in any judicial action; And that neither party may submit more than one interrogatory or deposition, nor shall a party take a deposition from the other-after having' submitted an interrogatory thereto, nor submit the. other party to an interrogatory after having taken a deposition, therefrom, except under exceptional circumstances which, in the judgment of the Court, justify the granting of another interrogatory or another deposition. The taking of depositions from the witnesses shall not be permitted without authorization of the court, after ascertaining the necessity of using said procedure.” Section 3 of Act No. 2 of October 17, 1961; 32 L.P.R.A. § 3120. (1961 Supp.).

Respondent’s conduct in requiring information from the claimant laborers which it already possessed was clearly inappropriate in the light of what was stated in Sierra and is sufficient justification for complainants’ action. Besides, since this ease concerns a law of procedural character, the provisions of the above-copied Act of 1961 are applicable to the facts of this case even though it was promulgated after the judgment of the court below. Fuentes v. Sec. of the Treasury, 80 P.R.R. 198 (1958); People v. Superior Court, 75 P.R.R. 501 (1953); Fajardo v. District Court, 69 P.R.R. 441 (1949); Pagán v. Otero, 69 P.R.R. 470 (1949); White Star Bus Line, Inc. v. District Court, 60 P.R.R. 348 (1942); Zayas v. Molina, 50 P.R.R. 619 (1936); Ojeda v. Gavilán, 46 P.R.R. 386 (1934); Hoek v. Bd. of Ed. of Asbury Park, 182 A.2d 577 (N.J. 1962); the same norm is applied in Spain, 1 Castro y Bravo, Derecho Civil de España 727 (3d ed. 1955).

*267There remains to be considered whether or not the trial judge was justified in dismissing the action because of the claimants’ failure to appear.9 He was not. Aside from the fact that plaintiffs should have appeared at the hearing to explain the reasons why they were in no condition to answer the interrogatories, the truth is that the case was not ready to be heard on its merits because of the fact that respondent had not yet answered the interrogatories submitted by the claimants. Cf. Ramirez de Arellano v. Sec. of the Treas., 85 P.R.R. 798 (1962), and Link v. Wabash Railroad Co., 370 U.S. 626 (1962).

In view of the foregoing, the judgment appealed from rendered by the Superior Court, Mayagiiez Part, on August 8, 1961, will be reversed and the case remanded for further proceedings.