concurring specially: I concur in the majority opinion’s holding that the trial court erred in denying the hospital’s motion for a rehearing, but disagree with its holding that the trial court properly raised the statute of limitations defense sua sponte. *401Whether the litigants appear pro se or are represented by counsel, it is the defendant’s responsibility to raise an affirmative defense, such as the statute of limitations, and failure to do so within a prescribed period of time should be deemed a waiver, see Yeaton v. Skillings, 100 N.H. 316, 320, 125 A.2d 923, 926 (1956); R. WlEBUSCH, 4 NEW HAMPSHIRE Practice, Civil Practice and Procedure § 292, at 200 (1984); cf. Shortlidge v. Gutoski, 125 N.H. 510, 516-17, 484 A.2d 1083, 1088 (1984) (failure to file plea of abatement in district court within thirty days will result in a waiver). It is undisputed that the Halls never filed a special plea or brief statement or otherwise raised the statute of limitations as a defense, and never sought an exception to Rule 3.10(A)’s thirty-day rule. Accordingly, I would read Rule 3.10(A) as foreclosing the defendants from enjoying the benefits of the defense.
The question then arises whether the trial court’s decision to disregard Rule 3.10(A) was justified under Rule 1.1, presumably because of the Halls’ status as pro se litigants. I recognize that “[t]he court’s essential function to serve as an impartial referee comes into direct conflict with the concomitant necessity that the pro se litigant’s case be fully and competently presented.” Austin v. Ellis, 119 N.H. 741, 743, 408 A.2d 784, 785 (1979). But while a judge may relax the rules of evidence for pro se litigants and explain courtroom procedures to them, see id., or even explain the relevant law to them, see State v. Brodowski, 135 N.H. 197, 200, 600 A.2d 925, 926-27 (1991), the judge’s constitutional obligations to remain impartial, N.H. CONST, pt. I, art. 35, and refrain from aiding litigants in the substance of a case are paramount. Raising an affirmative defense sua sponte, in my view, crosses the line from conscientiously explaining procedure to an inexperienced pro se litigant to intervening in the substance of a case on behalf of one of the parties. A pro se litigant should not receive a benefit from his or her decision not to retain the services of counsel. Accordingly, I would hold that the trial court’s action in raising the statute of limitations defense sua sponte was error.