CANTU, Justice.

This is an appeal from an order discharging the appellees, the Commissioners Court of Uvalde County, from a writ of mandamus on the basis that the writ had been complied with. The appellant, H.T. Vondy, was elected constable for Precinct 6, Uvalde County, Texas on November 4, 1978, and took office on January 17, 1979. Vondy filed an Application for Writ of Mandamus in the 38th District Court of Uvalde County on May 17, 1979, seeking to compel the appellees to set and pay him a reasonable salary. The application was denied. On appeal the Eastland Court of Appeals dismissed the cause on jurisdictional grounds. See Vondy v. Commissioners Court of Uvalde County, 601 S.W.2d 808 (Tex.Civ.App. — Eastland 1980).

The Supreme Court reversed and remanded the cause, and instructed the trial court to issue the writ sought by Vondy. The Supreme Court determined that the Texas Constitution, Article XVI, section 61 (Vernon Supp. 1986) as amended in 1972, mandates that the Commissioners Court compensate constables on a salary basis and that such salary be reasonable. Vondy v. Commissioners Court of Uvalde County, 620 S.W.2d 104, 108 (Tex. 1981) ("Vondy I"). The Supreme Court expressly rejected the appellees' arguments that they had the discretion to set no salary at all, that because no salary was set when Vondy accepted the office he could not now claim one, and that because no money was budgeted or available to pay Vondy there was no requirement to provide compensation for Vondy's services.

A writ of mandamus was issued by the trial court on September 17, 1981, ordering the appellees to set a reasonable salary and to extinguish the debt owed Vondy by virtue of his having held the office of constable. The writ further ordered the return of the writ by February 1, 1982, stating what was done in compliance with the writ.

The return was filed on January 27, 1982, wherein the appellees stated that on December 14, 1981, the Commissioners Court met and set a salary of $40.00 per month. The appellees tendered the sum of $960.00 into the registry of the court, representing payment of $40.00 per month for the 24 months Vondy was in office. The appellees also requested that they be discharged from any further duties under the writ.

Vondy objected to the proposed entry of an order discharging appellees, and filed a motion for contempt against the appellees. Vondy alleged that he was not afforded the opportunity for an evidentiary hearing to establish a record concerning the setting of a salary; that a salary of $40.00 per month was unreasonable and capricious and in violation of the mandate of the Supreme Court and the trial court; and that no interest was allotted for payment to Vondy.

A hearing was held on September 16, 1985, and a final judgment signed on October 9, 1985. The trial court discharged appellees from the writ, and denied Vondy's motion for contempt. All relief sought by Vondy was denied by the trial court except entitlement to the compensation set by appellees. All costs were assessed against Vondy.

Vondy presents four points of error. The first three allege that "the trial court erred in discharging the appellees from the writ of mandamus by finding as a matter of law" (1) that a salary of $40.00 per month is a reasonable salary for the office of constable; (2) that Vondy was not entitled to recover any expenses of office and (3) that Vondy was not entitled to any interest on the unpaid salary amounts from and after the date such payments were due.

Appellees argue that the trial court did not make findings as alleged by Vondy, and furthermore, that the trial court had no jurisdiction to make such findings. The appellees also attack Vondy's points of error as incorrectly failing to assign error on the part of the trial court, to-wit: in failing to state that the trial court erred in not finding that the Commissioners Court acted arbitrarily and abused its discretion.

The Texas Constitution, Article V, section 8 provides, in pertinent part:

The District Court shall have appellate jurisdiction and general supervisory control over the County Commissioners Court, with such exceptions and under such regulations as may be prescribed by law . . .

The legislature has not established a method or procedure for invoking the appellate jurisdiction or supervisory control of the district court over the Commissioners Court by any statutory enactment. Scott v. Graham, 156 Tex. 97, 292 S.W.2d 324 (1956). However, it is clearly established that the supervisory power of the district court can only be invoked when the Commissioners Court acts beyond its jurisdiction or clearly abuses the discretion conferred upon it by law. Yoakum County v. Gaines County, 139 Tex. 442, 163 S.W.2d 393 (1942). If the Commissioners Court does abuse its discretion, the district court has the power and authority to abrogate such actions. Bomer v. Ector County Commissioners Court, 676 S.W.2d 662 (Tex.App. — El Paso 1984, writ ref'd n.r.e.). Thus "this supervisory jurisdiction can be invoked in a direct attack in the district court when it is alleged that the Commissioners Court order is voidable as being arbitrary, capricious, unsupported by substantial evidence or that the court has acted beyond its jurisdiction." Mobil Oil Corp. v. Matagorda County Drainage District No. 3, 580 S.W.2d 634, 638 (Tex.Civ.App. — Corpus Christi 1979), rev'd on other grounds, 597 S.W.2d 910 (Tex. 1980).

Analyzing Vondy's points of error to determine the substance of the argument rather than the form of the allegations, as we are required to do under the liberal briefing rules, TEX.R.CIV.P. 422; Cleaver v. Dresser Industries, 570 S.W.2d 479 (Tex.Civ.App. — Tyler 1978, writ ref'd n.r.e.), Vondy's argument necessarily complains of the trial court's failure to find that the Commissioners Court acted arbitrarily and capriciously in setting Vondy's salary. In arguing that the trial court erroneously found that what the Commissioners Court did was reasonable, Vondy necessarily argues that the Commissioners Court's actions were unreasonable and an abuse of that court's discretion. Thus the real question before us is whether the district court erred in not finding that the Commissioners Court acted arbitrarily and capriciously and abused its discretion.

Additionally, we construe Vondy's objection or challenge to the appellees' motion for discharge from the writ of mandamus as a direct attack upon the order of the Commissioners Court. Therefore, Vondy has properly invoked the jurisdiction of the district court requiring it to exercise its supervisory control over the Commissioners Court by reviewing the order of the Commissioners Court. However, we note that the district court has no authority to set the salary of the constable. Rather, the Commissioners Court must determine what is a reasonable salary. See Vondy I, supra.

At the hearing before the trial court, Vondy offered testimony and evidence concerning what he considered to be a reasonable salary. Appellant testified that he worked at least 8 hours a day, 6 days each week performing duties as a constable for Precinct 6 during his term of office. Appellant stated that $650.00 would be a reasonable salary; and offered evidence that the two other constables of Uvalde County made $1,001.00 per month and $475.00 per month respectively, plus expenses. Vondy also presented evidence of his expenses incurred in performing his duties as constable, including approximately $3,500.00 spent in modifying a car for patrol purposes.

Four witnesses who were members of the Commissioners Court during the 1978 to 1981 period also testified. Each of these witnesses related that they felt "under the circumstances" $40.00 per month was a reasonable salary for the constable of Precinct 6. These circumstances included: (1) the lack of funds available to pay Vondy; (2) that Vondy knew when he sought and accepted the job that there was no salary; (3) that the Precinct 6 area had adequate law enforcement protection so there was no need for Vondy's services; and (4) that Vondy's concurrent involvement in a private security business presented a conflict in interest in having Vondy serve as constable. The major factor in determining the salary was that the Commissioners Court perceived a lack of need of Vondy's services, since they believed the constable functions were being adequately performed by others. Our review of the record also indicates that the commissioners were concerned with the lack of funds to pay Vondy. In fact, one of the commissioners, Norment Foley, testified that the Commissioners Court set the salary at $40.00 in an attempt to stall paying a larger salary until funds to do so were available.

The duties of a precinct constable are set out in TEX.REV.CIV.STAT.ANN. art. 6885 (Vernon 1960);

Each constable shall execute and return according to law all process, warrants, and precepts to him directed and delivered by any lawful officer, attend upon all justice courts held in his precinct and perform all such other duties as may be required of him by law.

Constables are also peace officers, TEX.CODE CRIM.PROC.ANN. art. 2.12 (Vernon Supp. 1986); with all of the duties imposed on such officers, including; the prevention of threatened injuries and death, TEX.CODE CRIM.PROC.ANN. art. 6.01-6.07 (Vernon Supp. 1986); the assisting of magistrates in the performance of their duties, TEX.CODE CRIM.PROC.ANN. art. 7.01-7.17 (Vernon Supp. 1986); and the execution of arrest warrants, TEX.CODE CRIM.PROC. art. 15.16 (Vernon Supp. 1986). Article 2.13 of the Code of Criminal Procedure also sets out duties imposed upon constables as peace officers:

It is the duty of every peace officer to preserve the peace within his jurisdiction. To effect this purpose, he shall use all lawful means. He shall in every case where he is authorized by the provisions of this Code, interfere without warrant to prevent or suppress crime. He shall execute all lawful process issued to him by any magistrate or court. He shall give notice to some magistrate of all offenses committed within his jurisdiction, where he has good reason to believe there has been a violation of the penal law. He shall arrest offenders without warrant in every case where he is authorized by law, in order that they may be taken before the proper magistrate or court and be tried. (Emphasis added).

Once Vondy was duly elected and qualified to serve as constable for Precinct 6, he was obligated to perform these duties prescribed by law. A failure to perform such duties could subject Vondy to prosecution under the Penal Code. See TEX.PENAL CODE ANN. § 39.01 (Vernon Supp. 1986).

In view of these numerous duties imposed upon Vondy, we find that, as a matter of law, $40.00 per month, or the equivalent of $.20 per hour for the time spent by Vondy in performance of his duties is unreasonable.

The record is replete with evidence that the Commissioners Court did not deliberate as to what would be a reasonable compensation for Vondy, but rather they considered only the need for Vondy's services. The Commissioners Court cannot attempt to restrict or abolish a constitutionally established office by refusing to reasonably compensate the holder of such office. The Commissioners Court also cannot attempt to abolish or restrict the office of constable by refusing to allow or by preventing the elected official from performing those duties required of him.

The El Paso Court of Appeals in Bomer v. Ector County, supra, noted that a commissioners court may elect to use other official departments (such as the sheriff's office) to perform those duties imposed upon constables (such as the service of process) as determined by an exercise of their discretion. However, the delegation of such duties does not eliminate the obligation of a constable to perform such duties where required by law to do so or if called upon to do so; nor does it relieve the Commissioners Court from compensating a constable for other services rendered or which he is obligated to perform. Moreover, the issue of the reasonableness of a $20.00 per month salary in Bomer was not before the appellate court as the appellants in that case testified that they did not perform their duties as constables.

The Uvalde Commissioners Court did not set Vondy's salary by evaluating the work performed by or required of Vondy, but considered only those factors previously rejected by the Supreme Court in Vondy I. Neither did the Commissioners Court exercise its discretion by assigning some of those duties imposed on Vondy to other law enforcement agencies as was done in Bomer. The appellees merely, without any reason or basis other than that already rejected as improper, set Vondy's salary at $40.00 per month. Such act was clearly arbitrary and capricious.

Although Vondy attempted to accept the burden of proving what a reasonable salary was at the district court hearing, we find that the appellees, because of their request for discharge from the writ of mandamus, had the burden of proving that the salary that they set was reasonable. This was not done. There is no evidence in the record supporting the implied finding that the salary set was reasonable. Thus, Vondy's first point of error complaining of the trial court's error in finding that such salary is reasonable is meritorious and is sustained.

In sustaining this point of error, we do not attempt to instruct the Commissioners Court as to what would be a reasonable salary. Such is a determination to be made by the Commissioners Court after proper consideration of relevant factors. Vondy I. See also White v. Commissioners Court of Kimble County, 705 S.W.2d 322 (Tex.App. — San Antonio 1986, no writ). We note however, that TEX.REV.CIV.STAT.ANN. art. 3912i Secs. 1 2 (Vernon 1966) provides that the Commissioners Court shall fix the salary of constables in counties with populations of less than 20,000 at not more than $5,000.00 per annum, or in counties of 20,000 to 46,000 at a salary of not more than $6,000.00 per annum. These maximums may be considered by the Commissioners Court in determining what a reasonable salary would be.

Points of error two and three complain of the trial court's failure to find that the Commissioners Court abused its discretion in failing to reimburse Vondy for expenses of office and failing to include interest on the unpaid salary amounts. The original application for writ of mandamus filed by Vondy and the writ itself, requested and required only that the appellees set and pay a reasonable salary for the office of constable of Precinct 6 of Uvalde County. Therefore, without expressing an opinion as to entitlement we simply do not consider these complaints as properly before us on appeal. Points of error two and three are overruled.

Point of error four complains of the trial court's error in assessing all costs of court against appellant. The opinion of the Supreme Court in Vondy I ordered that the appellees pay "all costs in this Court and the Court of Civil Appeals." We find that this order referred only to costs incurred in procuring the writ of mandamus. Nevertheless, as the successful party before this Court, Vondy is entitled to recover all court costs associated with seeking compliance with the writ from the appellees. Point of error number four is sustained.

The judgment of the trial court is reversed and the cause is remanded to the district court with instructions that appellees not be discharged from the writ of mandamus until a reasonable salary is set by the Commissioners Court for the constable of Precinct 6. All costs of this appeal are taxed against appellees.