OPINION
HENDLEY, Judge.Plaintiffs, father and daughter, recovered judgment from defendants in the respective amounts of $2,000.00 and $770.-00. Plaintiffs appeal. Plaintiff, father, asserts that the trial court erred in admitting evidence that he received sick-leave pay during the time he was unable to work due to an automobile accident allegedly caused by defendants’ negligence. This amount equaled his regular salary. Plaintiff, father, also contends that the trial court erred in not admitting evidence of lost earnings in addition to his salary. Both plaintiffs appeal asserting it was error to receive evidence, over objection, concerning previous injuries and physical conditions. We reverse.
Plaintiff Father — sick-leave pay.
Plaintiff testified he lost 185 hours of work after the accident and that this amount of time, based on his salary, equated to $1,060.00. He testified on cross-examination, over objection, that he received his regular salary during this time and further that it was in the nature of sick-leave pay.
Defendant contends that this was permissible cross-examination “since it tended to prove whether Mr. Martinez was off work.” We disagree. The only relevant issue was whether plaintiff was unable to work, not whether he was paid during the time he was not working. It was error to admit into evidence testimony regarding his employer’s payment of wages or sick-leave pay while plaintiff was unable to work due to his injury. Such evidence violates the collateral source rule. Trujillo v. Chavez, 76 N.M. 703, 417 P.2d 893 (1966).
As our Supreme Court stated in Mobley v. Garcia, 54 N.M. 175, 217 P.2d 256 (1950):
“. . . The right of redress for wrong is fundamental. Charity cannot be made a substitute for such right, nor can benevolence be made a set-off against the acts of the tort-feasor. [Citations omitted].”
To Mobley we add that a tort-feasor should not get the benefit of the contract between the employee and the employer. Annot, 52 A.L.R.2d 1451 (1957).
Plaintiff Father—lost earnings.
Since the cause must be remanded for a new trial we answer plaintiff, father’s, point relating to lost earnings in addition to his regular salary. Plaintiff had been “moonlighting” as a surveyor. In this connection he attempted to introduce a document which represented his calculations of how much extra money he had earned from surveying in the three months prior to the accident. He also attempted to introduce his Schedule C tax form to show how little he earned from the same source in the year following the accident. The court refused to admit the first document because it covered too short a period of time. Plaintiff then chose not to introduce the Schedule C since its relevance depended on establishing how much the plaintiff earned before the accident.
The general rule with regard to evidence of pre-injury earnings and a subsequent post-injury decrease in earnings is that plaintiff may put in evidence of actual pre-injury earnings for a reasonable period of time and evidence of the post-injury decrease in earnings. However, what is a reasonable period of time depends on the facts of each case. The determination of what is a reasonable period of time is a matter of judicial discretion and will not be overturned in the absence of an abuse of discretion. Jacobsen v. Poland, 163 Neb. 590, 80 N.W.2d 891 (1957); See generally Annot, 81 A.L.R.2d 733 (1962).
Most cases generally speak in terms of years and usually speak in terms of remoteness rather than recency. Here, plaintiff’s evidence went to the three months prior to the injury. The trial court held that the time involved was too recent. We cannot say, as a matter of law, that the trial court abused its discretion in not admitting plaintiff’s offered evidence.
Plaintiffs, Father and Daughter—prior injuries.
Defendants, over plaintiffs’ objection, elicited testimony of prior injuries of both plaintiffs. A review of the record fails to reveal that the previous injuries were medically connected to the subsequent injuries. The uncontradicted testimony by both plaintiffs was that they had completely recovered from the prior injuries. Plaintiffs’ medical expert testified that the injuries complained of were caused by the collision with the defendants.
Defendants contend that the inquiry into plaintiffs’ prior injuries was proper because it was relevant to the proximate cause of the plaintiffs’ complaints and because of the physical proximity of the complaints. Defendants appear to argue on the grounds that plaintiffs had a pre-existing condition. The record only discloses that the plaintiffs were fully recovered from their prior injuries. Failure to find the extent to which a pre-existing condition had been aggravated served as ground for reversal in Alvillar v. Hatfield, 82 N.M. 565, 484 P.2d 1275 (Ct.App.1971). Absent such a showing, testimony about previous injuries and physical conditions, not causally connected to the subject claims is not admissible. Kantor v. Ash, 215 Md. 285, 137 A.2d 661 (1958); See Alvillar v. Hatfield, supra; See generally Annot., 69 A.L.R.2d 593 (1960). The admission of such testimony was prejudicial for it tended to minimize the extent of plaintiffs’ injuries by portraying them as constantly beleaguered with medical problems in any event. Cf. Browning v. King, 159 Cal.App.2d 326, 324 P.2d 14 (1958).
Defendants contend that even if the admission of such testimony was prejudicial, the objections thereto were not sufficient to preserve the issue for review. Defendants contend that a motion for a mistrial was necessary in order to preserve the error. We disagree.
The declaration of a mistrial is a ruling which in effect states, as a matter of law, that the trial cannot stand because of the disregard of some fundamental prerequisite. Illinois Oil Co. v. Grandstaff, 118 Okl. 101, 246 P. 832 (1926); See generally 58 C.J.S. Mistrial p. 833 (1948) and cases cited therein.
Defendants’ reliance on Frank Bond & Son, Inc. v. Reserve Minerals Corp., 65 N.M. 257, 335 P.2d 858 (1959), for the proposition that under the circumstances of the instant case a motion for a mistrial is required, is misplaced. The rule in Bond is simply that matters which are not of record will not be considered on appeal.
Plaintiffs made their objections in accordance with R.C.P. 46, § 21-1-1(46), N.M.S.A. 1953 (Repl. Vol. 4, 1970). The objections were sufficiently definite to alert the trial court to the claimed vice and to preserve the issue for appeal. Section 21-2-1(20), N.M.S.A.1953 (Repl. Vol. 4, 1970) superseded by § 21-12-11, N.M.S.A. 1953 (InterSupp.1974) effective April 1, 1974. Further, plaintiffs’ motion for a new trial also alerted the trial court to the claimed vice. The admission of the testimony was reversible error as to both plaintiffs.
Reversed and remanded.
It is so ordered.
HERNANDEZ, J., concurs. SUTIN, J., dissents.