Section 38-6-4 - Per diem and mileage for witnessesA. Witnesses shall be allowed no fees for services, but shall receive per diem expense and mileage at the rate specified for nonsalaried public officers as provided in the Per Diem and Mileage Act [10-8-1 to 10-8-8 NMSA 1978] for that time in which attendance is required, with certification of the clerk of the court.B. The district judge in any civil case pending in the district court may order the payment of a reasonable fee, to be taxed as costs, in addition to the per diem and mileage as provided for in Subsection A of this section, for any witness who qualifies as an expert and who testifies in the cause in person or by deposition. The additional compensation shall include a reasonable fee to compensate the witness for the time required in preparation or investigation prior to the giving of the witness's testimony. The expert witness fee which may be allowed by the court shall be limited to one expert regarding liability and one expert regarding damages unless the court finds that additional expert testimony was reasonably necessary to the prevailing party and the expert testimony was not cumulative.C. The provisions of this section shall apply only to cases filed on or after its effective date.Laws 1887, ch. 40, § 1; C.L. 1897, § 1810; Code 1915, § 5898; C.S. 1929, § 155-104; 1941 Comp., § 20-104; 1953 Comp., § 20-1-4; Laws 1959, ch. 62, § 1; 1971, ch. 139, § 1; 1975, ch. 105, § 1; 1983, ch. 189, § 1.