— This case requires us to decide whether a worker is not disabled as a matter of law because he is actually working. The Department of Labor and Industries (Department) seeks review of a court of appeals decision affirming a jury verdict that James Adams was permanently and totally disabled. We affirm.
On April 16, 1979, James Adams injured his left knee while working as a hod carrier for Custom Masonry and filed an industrial insurance claim. From June 1979 through January 1980, Adams had three surgeries on the knee. He received vocational rehabilitation training in welding, but continued to have knee problems and was unable to work.
On May 25, 1982, the Department issued an order awarding Adams a permanent partial disability award. Adams appealed, and the parties stipulated to reopening the claim. In 1984, Adams had another surgery on the knee. His surgeon recommended that he refrain from work requiring deep knee bending, kneeling, crawling, or climbing. Adams initially received additional vocational counseling, but in July 1985, the Department found he was employable as a muffler installer and declined to offer further services. On November 20, 1985, the Department terminated Adams’ time-loss benefits. Adams moved for reconsideration.
On August 1, 1986, Adams took a job doing cement work on curbs and sidewalks. At this time, Adams was about forty-nine years old, was married, and had one child and two stepchildren at home. He had an eighth-grade education, but tested at a fourth-grade level. He testified that he took the job, despite his doctor’s advice, because he needed the money to feed his family. According to Adams, the work caused severe pain and swelling. Although he was laid off in the fall, Adams resumed this work during the 1987 construction season.
*227On October 30, 1986, the Department found Adams to be permanently partially disabled, made an award, and closed the claim. Adams asked for reconsideration, and when denied, appealed to the Board of Industrial Insurance Appeals (Board). The Board remanded Adams’ case to the Department for reopening, but on August 14, 1987, the Department issued an order adhering to its October 1986 order. Adams again appealed.
In August 1987, Adams saw a psychiatrist/neurologist for evaluation. The doctor found Adams to be suffering from depression causally related to the knee injury.
The administrative hearing on Adams’ appeal was held in the spring of 1988. The hearing examiner issued a proposed decision finding: (1) Adams was not totally disabled for the time he did not work1 during the period between the Department’s termination of benefits in November 1985 until the final determination in August 1987; (2) Adams did not have a psychiatric condition stemming from his industrial injury; and (3) Adams was not permanently and totally disabled as of August 1987.
Adams appealed to the Board, assigning error to the three findings of fact. The Board denied Adams’ petition for review, and Adams appealed to the superior court.
A jury trial was held June 14 and 15, 1990. Pursuant to RCW 51.52.110 and .115, evidence in the form of the certified Appeal Board record was read to the jury. The Department moved for a directed verdict as to each of the three issues. The trial court denied the motion, ruling each was a question of fact for the jury. The jury agreed with the Department as to Adams’ psychiatric condition, but found Adams to be permanently and totally disabled.
The Department appealed. Adams failed to file a responsive brief and was precluded from presenting oral argument. The court of appeals nonetheless affirmed the trial court, Adams v. Department of Labor & Indus., 74 Wn. App. 626, 875 P.2d 8 (1994), and the Department now *228appeals to this court. It contends the court of appeals should have reversed because: (1) Adams did not file a responsive brief; (2) Adams was not disabled as a matter of law because he was actually employed during a portion of the period in question; and (3) Adams produced insufficient evidence to prove his disability.2
The Department first argues the court of appeals should have reversed the trial court because Adams failed to file a responsive brief, thereby requiring the court of appeals to restrict its review to whether the Department made a prima facie showing of reversible error.
"When a party fails to file a brief, RAP 11.2(a) requires that party to be barred from presenting oral argument. The court of appeals therefore acted properly in precluding Adams from presenting oral argument.
In addition to this penalty in cases where the respondent has failed to file a brief, the court of appeals has also limited review to whether the appellant’s brief makes a prima facie showing of reversible error. See, e.g., Hobart Corp. v. North Cent. Credit Servs., Inc., 29 Wn. App. 302, 303, 628 P.2d 842 (1981); State v. Wilburn, 51 Wn. App. 827, 829-30, 755 P.2d 842 (1988). In at least one case, the court of appeals has applied this same treatment to issues to which the respondent has not replied, even though the respondent has filed a brief. Bolt v. Hurn, 40 Wn. App. 54, 60, 696 P.2d 1261, review denied, 104 Wn.2d 1012 (1985).
This lowered standard of review developed prior to July 1, 1976, under the Court of Appeals Rules on Appeal (CAROA), then in effect. Wilburn, 51 Wn. App. at 828. CAROA 41(3) provided: "If the respondent files no brief, the cause will be deemed submitted upon its merits as to him.” The Rules of Appellate Procedure, which succeeded CAROA in 1976, contain no comparable provision, but in *229some cases the court of appeals continued without comment its earlier treatment of respondents failing to file briefs. E.g., Hobart, 29 Wn. App. at 303; Bolt, 40 Wn. App. at 60.
In Wilburn, however, the court examined the prima facie error doctrine in light of the new rules, and in a split decision, upheld its viability. While it was perhaps understandable that the court was displeased with a county prosecutor’s failure to file a brief, the court did not articulate any specific authority for the use of a lower standard. It simply ruled the respondent was obligated to file a brief, and the court could therefore sanction a party failing to file. Wilburn, 51 Wn. App. at 829. The dissent argued that although the respondent runs a great risk by not filing a brief, there was no longer any statutory authority for the penalty imposed by the court. Wilburn, 51 Wn. App. at 833-34 (Alexander, J., dissenting).
We find the dissent more persuasive. A respondent who elects not to file a brief allows his or her opponent to put unanswered arguments before the court, and the court is entitled to make its decision based on the argument and record before it. The court, however, should not confine itself to whether the appellant has presented a prima facie case when the record and their own knowledge of the law permit a fuller review. Under the RAPs, there is no longer a basis for differing standards of review. Even more importantly, the prima facie case rule has the potential for producing an unjust result. The quantity or quality of briefing should not affect the standard of review used by the court.
The Department next contends the trial court erred in not finding as a matter of law Adams was not permanently and totally disabled within the meaning of RCW 51.08.160 because he was actually working at his preinjury job.
The industrial insurance statute defines "permanent total disability” as: "loss of both legs, or arms, or one leg and one arm, total loss of eyesight, paralysis or other condition permanently incapacitating the worker from *230performing any work at any gainful occupation.” RCW 51.08.160. While the statutory language is usually a good starting place for statutory interpretation, we have long recognized the difficulty in applying the above definition to the variety of cases in our courts. See Leeper v. Department of Labor & Indus., 123 Wn.2d 803, 810-11, 872 P.2d 507 (1994). We require trial courts to supplement the statutory definition with case law. Buell v. Aetna Casualty & Sur. Co., 14 Wn. App. 742, 744, 544 P.2d 759 (1976).
The definition that has emerged from case law has both a medical aspect—the extent of physical impairment—and an economic aspect—the effect on wage-earning capacity. Leeper, 123 Wn.2d at 812. These two aspects are combined in the standard jury instruction that "a worker is totally disabled if unable to perform or obtain regular gainful employment.” WPI 155.07 (3d ed. 1989). The extent of physical impairment relates to ability to perform while the effect on wage-earning capacity relates to ability to obtain employment. See Leeper, 123 Wn.2d at 814. The resulting definition is
a hybrid quasi-medical concept in which there are intermingled in various combinations, the medical fact of loss of function and disability, together with the inability to perform and the inability to obtain work as a result of [the] industrial injury.
Fochtman v. Department of Labor & Indus., 7 Wn. App. 286, 294, 499 P.2d 255 (1972).
The Department’s argument that Adams is not disabled focuses solely on wage-earning capacity, relying almost entirely on Turner v. Department of Labor & Indus., 41 Wn.2d 739, 251 P.2d 883 (1953). The worker in that case, a carpenter, suffered brain damage as a result of a fall, causing headaches, dizzy spells, personality changes, and some loss of hearing, memory, and reasoning skills. Turner, 41 Wn.2d at 741. Despite his injuries, the worker took a job as a millwright, and had been working for about nine months when the Department closed his claim. Turner, 41 Wn.2d at 742.
*231The worker appealed the Department’s decision to the superior court. Turner, 41 Wn.2d at 740. After the case in chief had been read into the record, the Department challenged the sufficiency of the evidence and moved for dismissal. The court granted the Department’s motion, and the worker appealed. Turner, 41 Wn.2d at 740.
This court affirmed, holding the worker was steadily employed and therefore not permanently and totally disabled. Turner, 41 Wn.2d at 743. In so holding, however, the court noted the worker had produced no evidence that "his working caused him serious discomfort or pain or that his life or health was endangered thereby.” Turner, 41 Wn.2d at 743.
The Turner court noted the lack of medical evidence distinguished its case from Kuhnle v. Department of Labor & Indus., 12 Wn.2d 191, 120 P.2d 1003 (1942). Kuhnle involved an injured logger who was supervising the operation of a family farm. Kuhnle, 12 Wn.2d at 192, 196. Found by the Department to be partially disabled, the logger appealed to the superior court, asserting a permanent total disability. Kuhnle, 12 Wn.2d at 192. The court sustained a challenge to the sufficiency of the evidence and the logger appealed. Kuhnle, 12 Wn.2d at 192.
In Kuhnle, as here, the Department argued the fact the worker was employed was determinative. This court reversed, observing that inability to perform did not mean "that the workman must be absolutely helpless or physically broken and wrecked for all purposes except merely to live.” Kuhnle, 12 Wn.2d at 197. The court found intermittent or limited earning capacity did not necessarily reduce a total disability to a partial one because a reasonable degree of continuity was implied by the statute. Kuhnle, 12 Wn.2d at 197 (citing Green v. Schmahl, 202 Minn. 254, 256, 278 N.W. 157 (1938)).
Thus, this court’s cases—including Turner— uniformly support the proposition that permanent total disability is a question involving more than just the worker’s employment status on a given day. Providing the *232worker produces sufficient evidence of loss of earning capacity and expert medical evidence that working causes serious discomfort or pain or puts his or her life or health in immediate danger, total disability is a question for the jury. Therefore, the trial court in this case correctly rejected the Department’s argument that Adams’ employment status alone meant he was not disabled as a matter of law based on Turner.
The Department also argues, if Adams could be disabled while working, then res judicata principles would prevent the Department from ever terminating his pension, in contravention of RCW 51.32.160. This section, in pertinent part, provides:
If aggravation, diminution, or termination of disability takes place, the director may . . . readjust the rate of compensation in accordance with the rules in this section provided for the same, or in a proper case terminate the payment ....
If a worker receiving a pension for total disability returns to gainful employment for wages, the director may suspend or terminate the rate of compensation established for the disability without producing medical evidence that shows that a diminution of the disability has occurred.
This section in no way conflicts with the trial court’s ruling. Adams was not employed at the time he began receiving pension benefits. He neither sought nor received benefits for periods during which he actually worked. If he now returns to work, this section will allow the Department to suspend his pension. The Department’s argument is not persuasive.
Finally, the Department argues Adams did not produce sufficient evidence that he could not perform light or sedentary work of a general nature, precluding a finding of total disability under Herr v. Department of Labor & Indus., 74 Wn. App. 632, 875 P.2d 11 (1994). We disagree. Although Adams’ treating physician, Dr. Brewster, testified Adams was capable of gainful employment within certain *233physical limitations, Adams’ vocational counselor testified to other limitations. He stated that, in view of Adams’ physical and educational limitations, his skills, his potential for retraining, and the conditions of the general job market, Adams was not capable of gainful employment in the general labor market with any degree of success and continuity. In view of this evidence, the trial court acted properly in submitting the question of Adams’ disability to the jury.
While it may seem anomalous that a worker can be adjudged disabled while working at his or her preinjury job, the purpose behind RCW Title 51 is to insure against the effective loss of wage-earning capacity. Kuhnle, 12 Wn.2d at 197. Wage-earning capacity means sustainable wage-earning capacity and working in great pain is not sustainable. While it would be easier for the Department and the courts to set a certain amount of time which would, as a matter of law, establish sustainable wage-earning capacity, such a rule would undoubtedly work an injustice in some cases. The question of disability is better suited to an individualized jury determination than a bright line rule.
We therefore affirm.
Dolliver, Smith, Madsen, Alexander, and Pekelis, JJ., concur.
Adams had not asked for any benefits for the time he actually worked.
At oral argument, the Department also contended the trial court erred in instructing the jury on the meaning of permanent total disability. This argument was briefed to the court of appeals, which upheld the instruction. However, the Department did not raise the issue in its petition for review to this court. Therefore, review is precluded under RAP 13.7(b).