OPINION
MAUZY, Justice.This cause requires us to examine the scope of the Fire Fighters’ and Police Officers’ Civil Service Act, formerly Tex.Rev. Civ.Stat.Ann. art. 1269m,1 now codified at sections 143.001-143.134 of the Texas Local Government Code (“the Act”). Petitioners, officers in the Houston Police Department, assert that the Act entitles them to promotion with back pay, in addition to declaratory and injunctive relief. The court of appeals reversed the trial court’s judgment granting the requested relief, and rendered a take-nothing judgment against the police officers. 762 S.W.2d 180 (1988). In so ruling, the court of appeals held that the Act applies only to positions requiring the performance of law enforcement duties. Id. at 186-87. Because we disagree with that construction of the Act, we reverse the judgment of the court of appeals and remand the cause to the trial court for entry of judgment in accordance with this opinion.
The actions challenged in this suit reflect the City of Houston’s ongoing effort to “civilianize” the Houston Police Department (HPD). The court of appeals opinion sets out the pertinent aspects of that effort. In short, the City placed unclassified civilians in managerial positions traditionally held by classified police officers. Petitioners allege that those placements contravened the Act.
The purpose of the Act, as stated in section 143.001, is “to secure efficient fire and police departments composed of capable personnel who are free from political influence and who have permanent employment tenure as public servants.” To that end, the Act requires the city council, or other legislative body, to provide by ordinance for the classification of all fire fighters and police officers; that is, to place all such officers within the protection of a civil service system. Section 143.021. The proper boundaries of that system, however, are unclear.
In its original form, the Act defined “policeman” as
any member of a Police Department who draws compensation for his services as a member of said department.
Tex.Rev.Civ.Stat.Ann. art. 1269m, § 2, Act of June 2, 1947, 50th Leg., R.S., ch. 325, 1947 Tex.Gen.Laws 550, 551. Applying that definition, courts uniformly rejected attempts to remove any police department positions from civil service protection; all employees were protected by the Act. See City of San Antonio v. Handley, 308 S.W.2d 608, 610 (Tex.Civ.App.—San Antonio 1957, writ ref’d), and cases cited therein.
With a 1957 amendment, however, the Act’s definition of “policeman” became less clear, encompassing
any member of the Police Department appointed to such position in substantial *292compliance with the provisions of Sections 9, 10, and 11 of this Act ...
Act of June 6, 1957, 55th Leg., R.S., ch. 391, § 1, 1957 Tex.Gen.Laws 1171.2 Sections 9,10, and 11 of article 1269m required competitive examinations for appointment to positions in the police department. The codified version of that language, located at section 143.003(5) of the Local Government Code, provides simply that a “police officer” is one who was appointed in substantial compliance with chapter 143 of the code. Thus, since 1957, the Act’s most important definition has been circular. Section 143.003(5) states, in essence, that the Act covers whomever the Act covers.3
In the years since 1957, a number of courts have addressed questions regarding the coverage of the Act. Almost all of those cases, however, have involved individuals employed prior to 1957, who automatically maintained their civil service status after the amendment. See, e.g., City of San Antonio v. Carr, 161 Tex. 155, 338 S.W.2d 122, 124 (1960); Clack v. City of San Antonio, 452 S.W.2d 502, 503 (Tex.Civ.App.—San Antonio 1970, writ ref'd n.r.e.).
One prior court has probed the impact of the 1957 amendment. In City of Wichita Falls v. Harris, 532 S.W.2d 653 (Tex.Civ.App.—Fort Worth 1975, writ ref’d n.r.e.), the City had hired a “fire training specialist” without following the procedures set out in the Act for the hiring of classified officers. Eight members of the fire department then brought suit to void the city’s appointment. The trial court found that the new position fell within the coverage of the Act. In reviewing that finding, the court of civil appeals noted the fundamental circularity of the Act’s terms:
If the Act is construed strictly it would mean that the City could employ new firemen who would not be under Civil Service by simply not giving them an examination. The City acknowledges that this is obviously not the intent of the legislature.
Id. at 657. To avoid defeating the intent of the legislature, the court construed the Act as a whole. Looking to the job description for the new position, the court observed that “a person holding the position must have knowledge of the principles and practices of fire prevention and suppression.” Id. at 656. On that basis, the court affirmed the trial court’s finding that the position was within the ambit of the Act.
The court of appeals in the present case took a different approach. While noting that the Act should be viewed as a whole, the court placed special reliance on the predecessor to section 143.023(e), which now provides:
An applicant may not be certified as eligible for a beginning position with a police department unless the applicant meets all legal requirements necessary to become eligible for future licensing by the Commission on Law Enforcement Officer Standards and Education.
The only positions that require law enforcement training, the court reasoned, are those that involve traditional law enforcement duties. Thus, the court concluded that the Act encompasses only those employees who actually do “police work;” that is, those who enforce the law, make arrests, and conduct criminal investigations. We disagree.
Nothing in either the language or the history of section 143.023(e) evinces a legislative intent to limit the coverage of the Act. The legislature adopted that provision in 1985, almost forty years after it originally passed the Act. Tex.H.B. 1657, *293Act of May 26, 1985, ch. 910, § 4, 69th Leg., R.S., 1985 Tex.Gen.Laws 3046, 3047. If, in passing H.B. 1657, the legislature had intended to restrict the coverage of the Act, it would have amended the statutory provision which purports to establish the Act’s scope — namely, section 2 of article 1269m, now codified at section 143.003(5) of the Local Government Code. Notably, on the day after it took final action on H.B. 1657, the 69th Legislature demonstrated that it knew full well how to alter the coverage of the Act. With its adoption of S.B. 540, the legislature extended the coverage of the Act to include specialized police forces, such as park police, airport police, and city marshals, in any city having a population of 1,500,000 or more. Tex.S.B. 540, Act of May 27, 1985, ch. 958, § 22, 69th Leg., R.S., 1985 Tex.Gen.Laws 3227, 3241.4 To do so, the legislature amended section 2’s definition of “policeman” by adding a reference to section 14B, a new section governing such police forces, now found at section 143.103 of the Local Government Code. H.B. 1657, in contrast, did not mention section 2.
The City argues that a broad construction of the Act would bring section 143.-023(e) into conflict with the Act’s objective, stated in section 143.001, of promoting efficiency in the police force. If only licensed police officers can hold managerial positions, the argument goes, then the HPD will be unable to utilize the talents of civilians. The premise of that argument is invalid. Section 143.023(e) does not require that all applicants be licensed police officers. Rather, that section requires, by its terms, that applicants meet the requirements necessary to become eligible for future licensure. Any civilian meeting those requirements may apply for a beginning position; and once hired, that individual may become eligible for promotional positions. Under the Act, promotions are determined by performance on promotional examinations, for which any classified employee — licensed or unlicensed — may sit, as long as the employee meets certain basic requirements. Section 143.028.
Certainly, there might be instances in which a police department would prefer to hire someone from outside the department, rather than to promote from within. We must presume, however, that the legislature took that possibility into account when it created the Act. Our function is not to question the wisdom of the statute; rather, we must apply it as written. Jones v. Del Andersen and Associates, 539 S.W.2d 348, 351 (Tex.1976). Moreover, the legislature might reasonably have concluded that the goal of efficiency would be well served by requiring merit-based promotions within the department, rather than giving the department a free hand to hire from without. See Note, Absolute Preferences in Municipal Civil Service Appointments: The Unresolved Conflict With Municipal Discretion, 64 Mich.L.Rev. 891, 896-97 (1966).
Other provisions, in addition to section 143.023(e), indicate that the legislature intended the Act to have broader application than the court of appeals suggests. Section 143.025(b) requires all applicants to take tests based on “police work and work in the police department,” suggesting that the Act’s reach extends beyond the performance of traditional “police work.” Section 143.102 gives the Chief of Police of a large municipality authority to appoint persons to certain command staff positions,5 suggesting that the Act would oth*294erwise require competitive testing for those positions. Section 143.109, which similarly applies only to a large municipality, prohibits crossover promotions of classified employees in specialized technical areas, suggesting that the legislature contemplated the inclusion of at least some members of the technical classes within the civil service system.
In the absence of a clear definition of “police officer,” courts should determine the scope of the Act by viewing the statute as a whole. The Act applies to any position requiring a competitive examination. Sections 143.003, 143.021(c).6 Such an examination tests an applicant’s “knowledge of and qualifications for ... police work and work in the police department,” as well as the applicant’s “general education and mental ability.” Section 143.-025(b).7 We conclude, then, that the Act applies to any position requiring proficiency in all of those areas. If a particular position requires substantial knowledge of “police work and work in the police department,” then it must be classified. Conversely, if a position requires no knowledge of such work, then the position need not be classified.8 Where the duties and functions entailed by a particular job are undisputed, the determination of whether that job requires knowledge of police work and work in the police department is a question of law for the court.
We recognize that this holding may not resolve all doubts as to whether the Act covers particular positions. However, the legislature’s failure to draw a bright line does not, in itself, authorize a court to draw one of its own. It is the obligation of the legislature, rather than the courts, to develop a workable definition of “police officer.” See Tex. Const, art. II, § l.9 A *295court may not judicially amend a statute and add words that are not implicitly contained in the language of the statute. Jones v. Liberty Mutual Ins. Co., 745 S.W.2d 901 (Tex.1988).
Moreover, the standard we discern today should, in most cases, produce an unequivocal answer as to whether a particular position must be classified. The average patrol officer’s duties certainly require knowledge of police work and work in the police department; to that extent, the average patrol officer’s position must be classified. On the other hand, the duties of an ordinary clerk-typist in the police department do not require knowledge of police work and work in the police department; so to that extent, the clerk-typist’s position need not be classified.
When the duties of a particular position fall outside the scope of the Act, the City may abolish the position, provided it does so in good faith. Moncrief v. Tate, 593 S.W.2d 312 (Tex.1980). As long as the position remains within the civil service system, however, any person holding the position is entitled to the full protection of the Act.
One critical aspect of civil service protection is the right to seek promotion by way of competitive examinations. Section 143.031. For every classified employee, the civil service system offers a career ladder, whereby the officer may work his or her way upward through the ranks. The various ranks, like rungs on a ladder, must comport with the system as a whole; that is, they must be filled by competitive examination, open to all who meet the basic statutory requirements. The Act does provide special procedures for appointment to positions at the very top of the ladder. Sections 143.013, 143.014, 143.102. At subordinate levels, however, the civil service ladder must remain intact.10 All positions in the civil service hierarchy—that is, all classified positions, and all positions entailing the supervision of classified employees—must be classified, and all appointments to those positions must be made in accordance with the Act. See International Ass’n of Firefighters v. Townsend, 622 S.W.2d 562, 563 (Tex.1981).
Evidence in the present case indicates that the City “declassified” certain top-level job assignments within the HPD. The trial court found that four newly-hired, unclassified employees were performing the same duties, and exercising the same supervisory responsibilities, as deputy chiefs of police, while five others assumed the duties and responsibilities of lieutenants. The unclassified employees occupy positions which involve the supervision of classified police and which are thus integral parts of the HPD’s civil service hierarchy. Accordingly, the placement of unclassified employees in those positions contravened the Act.
We do not hold that every high-level position in a police department must be held by a classified employee. If a particular job assignment requires no knowledge of police work and work in the police department, and entails no supervision of classified officers, the position need not be classified. Thus, the Act does not necessarily prohibit the vertical declassification of certain subdivisions within the department. Nor does the Act prohibit the holder of a police license from assuming a job assignment outside of the civil service system, when the assignment requires no knowledge of police work and work in the police department, as defined above.
The Act does, however, prohibit horizontal declassification across upper levels of bureaucratic subdivisions, when classified employees hold subordinate positions within those subdivisions. The removal of such upper-level positions from the civil service system would expose critical job assignments to political influence, and would obstruct the upward progress of classified *296employees. Such declassification would thus thwart the Act’s aim of securing efficient police departments. Section 143.001.
We hold that the challenged placements contravened the Act’s requirement that all covered positions be filled in accordance with the statutory terms. Section 143.-021(c).11 We therefore reverse the judgment of the court of appeals and remand the cause to the trial court for entry of judgment in accordance with this opinion.
Dissenting opinion by GONZALEZ, J., joined by CORNYN, J.. Act of June 2, 1947, 50th Leg., R.S., ch. 325, 1947 Tex.Gen.Laws 550, as amended, repealed by Act of May 1, 1987, ch. 149, § 49(1), 1987 Tex.Gen.Laws 1306. The actions giving rise to this suit took place prior to codification, and are therefore governed by article 1269m. However, because codification entails no substantive change, see Tex.Loc.Gov't Ann. § 1.001, this opinion refers to the codified version of the statute, except where otherwise noted.
. In 1985, the legislature changed the definition again by adding a reference to officers in specialized police forces, and by adding the words “or other peace officer" after the word "Department.” Act of May 27, 1985, 69th Leg., R.S., ch. 958, § 21, 1985 Tex.Gen.Laws 3227, 3241 (discussed infra at 297-298).
. Though the parameters of the Act are unclear, the mandatory character of the Act is plain. Section 143.021(c) unequivocally states that "a position or classification ... may be filled only from an eligibility list that results from an examination held in accordance with this chapter.” That requirement is binding. International Ass’n of Firefighters v. Townsend, 622 S.W.2d 562 (Tex.1981). To hold otherwise, as the dissent suggests, would be to nullify the Act as a whole.
. In 1983, the legislature apparently tried to effect that change by amending section 14A of article 1269m. Act of June 19, 1983, 68th Leg., R.S., ch. 517, 1983 Tex.Gen.Laws 3006, repealed by Act of June 16, 1985, 69th Leg., R.S., ch. 958, § 21, 1985 Tex.Gen.Laws 3227, 3240-41. The City of Houston, however, refused to interpret that amendment in a manner which would extend all provisions of article 1269m to the specialized police forces. Senate Committee on Intergovernmental Relations, Bill Analysis, S.B. 540, 69th Leg., R.S. (1985). Consequently, the Iegislature acted in 1985 to achieve its aim directly. Id.
. Subchapter G of the Act, which contains section 143.102, generally applies only to a municipality with a population of 1.5 million or more. Section 143.101(a).
Section 143.102 authorizes the Chief of Police to “appoint a person to a command staff position at the rank of assistant chief." Section 143.102(a). This suit involves the placement of civilians in positions which are allegedly the equivalent of deputy chief positions; that is, *294positions which are immediately below the rank of assistant chief. Thus, section 143.102 is not directly applicable to this suit. We note, however, that legislative efforts to authorize the Chief of Police to appoint deputy chiefs have consistently failed. See Tex.H.B. 1590, H.B. 1697, H.B. 2218, and S.B. 1187, 71st Leg., R.S. (1989).
. In article 1269m, see sections 2, 8(b), 9(a), and 12(c).
. The local Fire Fighters’ and Police Officers’ Civil Service Commission must provide for “open, competitive, and free” entrance examinations, § 143.025, and must also provide for fair promotional examinations, § 143.032. Neither section requires that the commission provide the same test for every classification or position. Rather, the commission may design whatever tests are necessary to meet the particular needs of the department, as long as the tests meet the basic requisites of those sections. See generally Note, Civil Service Commission — Civil Service Commissions are Generally Accorded Wide Discretion by the Courts in the Preparation and Administration of Examinations to Meet the Public Demand for the Employment of Individuals in the Public Service, 30 Drake L.Rev. 650-52 (1980-81).
Similarly, the commission is authorized to specify age and physical requirements for beginning and promotional positions, and to require appropriate physical examinations. Section 143.022. For any given position, the requirements must be the same for all applicants; but nothing in the Act requires the commission to apply the same requirements to every classification or position. Thus, the dissent is flatly wrong in suggesting that a computer genius who is thirty-seven or who has a physical disability is forever barred from supervising the police computer department. Assuming, without deciding, that such a position must be classified, the commission has as much latitude in crafting requirements for that position as it does for any other.
. “Police work,” in our view, refers to traditional law enforcement functions. Any broader interpretation would render the phrase redundant. The second half of the phrase, i.e, "and work in the police department,” encompasses other activities within the department.
Of course, virtually every position may require some knowledge of "work in the police department.” However, to apply the Act on that basis alone would be to ignore the conjunctive term “and.” The Act applies only to those positions requiring knowledge of “police work and work in the police department." Some positions requiring knowledge of work in the police department may not require knowledge of police work; consequently, those positions need not be classified.
. We note that the Act, as a whole, has not suffered from legislative inattention. Since the adoption of the new definition of “policeman,” the legislature has amended the statute at least thirty-two times. In none of those instances, however, did the legislature address the opaqueness of the statute’s most basic provision. Until the legislature clearly defines the scope of the Fire Fighters' and Police Officers’ Civil Service System, courts will be left to apply the vague standard we discern today to increasingly complex bureaucracies.
. In a city with a population of 1.5 million or more, such as Houston, the Act provides for distinct ladders within specialized police divisions and classes. Section 143.103. Officers in such divisions are still accorded the benefit of all other provisions in the Act, "including the provisions relating to eligibility lists, examinations, promotions, appointments,” etc. Section 143.103(c).
. In article 1269m, see section 8(b).
We do not reach the Petitioners’ contention that the Respondents' actions amounted to abolition of existing classified positions. See City of San Antonio v. Wallace, 161 Tex. 41, 338 S.W.2d 153 (1960).