(dissenting). Respectfully, I dissent. I am unable to agree, for the reasons delineated below, with the majority’s construction of the ordinance at issue.
My principal disagreement with the majority opinion centers upon the “not less than one-half” phrase. In the majority’s view, this phrase, reading the ordinance as a whole, authorizes “a payment of a pension beyond the amount of 50 percent of a retiree’s annual salary only when an additional pension is earned by additional years of service.” I cannot agree.
It is a settled principle of statutory construction “that ‘[n]o word in a statute should be treated as superfluous, void or insignificant unless there are impelling reasons . . . why this principle cannot be followed.’ Levin-Townsend Computer Corporation v. Hartford, [166 *473Conn. 405, 409, 349 A.2d 853 (1974)].” (Citations omitted.) State v. Burney, 189 Conn. 321, 327, 455 A.2d 1335 (1983). “There is a presumption of purpose behind every sentence, clause or phrase in a legislative enactment so that in construing it no part is to be treated as insignificant and unnecessary.” Connecticut Light & Power Co. v. Costle, 179 Conn. 415, 422, 426 A.2d 1324 (1980). In its construction of § 5 (a), the majority effectively reads the “not less than” phrase out of the ordinance by rendering it superfluous and of no force.1
Moreover, although it is true that ambiguous phrases should not be considered in isolation but in the context of the statute as a whole; Mitchell v. King, 169 Conn. 140, 144, 363 A.2d 68 (1975); I discern nothing in the language of § 5 (a) which justifies the conclusion that “not less than one-half” means exactly one-half. Indeed, in my view, the construction of “not less than one-half” according to its “commonly accepted meaning”; State v. Burney, supra, 326; General Statutes § 1-1 (a); compels the conclusion that while the pension awarded must be one-half of the preretirement salary, it may be higher. There is ample support for the proposition that the phrases “at least” or “not less than,” while mandating a minimum, do not establish a maximum as well. See, e.g., Turley v. Bolin, 27 Ariz. App. 345, 348-50, 554 P.2d 1288 (1976) *474(the phrase petitions “shall be filed . . . not less than four months preceding the date of election” reserves a minimum filing deadline and implies the right to file at any time prior to four months); Peters v. Fenner, 294 Minn. 488, 489, 199 N.W.2d 795 (1972) (where contract contained language requiring buyer to make monthly payments of “not less than $223.84,” “not less than” confers on purchaser an unqualified right to prepay entire amount in any month); People v. Jackson, 27 App. Div. 2d 943, 279 N.Y.S.2d 259 (1967) (“not less than” not to be construed as equivalent to “not more than”).
I also cannot agree with the majority that such a construction of “not less than” would confer “unfettered” or “unlimited” discretion upon the board. In this regard it is helpful to note, first, the mandatory language contained within § 5 (a). The section provides that the board (1) shall pay retirees with at least twenty-five years of service an amount equal to not less than one-half of their preretirement salary; (2) shall pay such retirees an additional 2 percent of their salary for each year over twenty-five; (3) but in no event shall the pension awarded exceed 70 percent of an employee’s preretirement salary.
We have consistently held that the use of the word “shall” in a statutory context ordinarily connotes a duty the character of which is mandatory and not permissive. Burwell v. Board of Selectmen, 178 Conn. 509, 517, 423 A.2d 156 (1979); Morris v. Timenterial, Inc., 168 Conn. 41, 43, 357 A.2d 507 (1975). The board, therefore, must pay a twenty-five year retiree 50 percent of his salary, must provide an additional 2 percent for each year over twenty-five, and must not award a pension which exceeds 70 percent of the employee’s salary. I do not read the majority opinion to hold otherwise.
*475In light of these mandatory directives, I cannot agree that § 5 (a) confers “unfettered” discretion upon the board. Under no circumstances may the board award a pension in any amount below 50 percent or above 70 percent of a retiree’s salary. As a retiree’s length of service extends beyond twenty-five years, the board’s discretion becomes correspondingly narrower until it disappears altogether regarding employees with thirty-five or more years of full-time service. In the present case, for example, it cannot be disputed that pursuant to the mandatory provisions of § 5 (a), Chief Howell is entitled to a pension of 62 percent of his former salary. The degree of discretion vested in the board, therefore, is limited to 8 percent of that salary. If the “not less than” phrase is given its common and ordinary meaning consistent with the overall statutory scheme, the language confers upon the board the discretion to award that percentage of a retiree’s preretirement salary, between a minimum of 50 percent and a maximum of 70 percent, which has not been provided for by the additional 2 percent for each year of full-time service over twenty-five years. Thus, if a retiree elects retirement after exactly twenty-five years, the ordinance vests in the defendant discretionary power to award any additional sum but only up to a maximum of 20 percent of the preretirement salary.
The majority asserts that even if it is assumed, arguendo, that the ordinance may reasonably be interpreted in this manner, it nevertheless interprets the position of the board, based on the record before us, as expressly disclaiming reliance on such a formula. According to the majority, the defendant’s position, with which it disagrees, is simply that the board is vested with discretion, regardless of years of service beyond twenty-five years, to set the minimum pension award at any amount between 50 and 70 percent, inclusive. *476Because of the mandatory “pension ladder” delineated within § 5 (a), as well as the mandate that a pension must not exceed 70 percent of salary, I agree that this is an erroneous interpretation of the statute, although I do not agree that this was in fact the position of the board.
A fair interpretation of the testimony elicited at trial rebuts the majority’s conclusion that the board, by expressly disclaiming reliance on the 2 percent formula, construed its discretion as “unfettered” between a minimum of 50 percent and a maximum of 70 percent. Steven Alderman, a trustee of the defendant board and the only witness to testify at trial, commented at length concerning the criteria utilized by the board in arriving at the pension at issue. It is clear that the dominant consideration, in light of Chief Howell’s employment history and service to the community, was to reward him with a pension at the same percentage of salary, 70 percent, as the previous fire chief. Alderman expressly acknowledged, however, that the board considered the years of service beyond the twenty-five year minimum,2 as well as the language contained within the ordinance itself.3 Although Alderman stated that the board did not follow the “two percent formula,” a fair reading of this testimony is not that the board chose to eschew the clear mandatory language of § 5 (a), but that the board chose not to limit itself exclu*477sively to the formula. Strict adherence to the “two percent formula” would limit Chief Howell’s pension to 62 percent of his preretirement salary, and clearly, in light of his employment history, the board wished to award him the maximum amount permissible under the ordinance.4
To construe the board’s position as authorizing it to award a pension in any amount between 50 and 70 percent, inclusive, regardless of years of service beyond twenty-five years, effectively labels the actions of the board as a deliberate flouting of the mandatory provisions of § 5 (a). It is unreasonable to conclude that pursuant to its efforts to award Chief Howell a 70 percent pension, the board eschewed the precise and mandatory power which allowed it to attain the 62 percent plateau without the exercise of discretion. Even if it is assumed that the evidence elicited at trial is equivocal concerning the exact method utilized by the board in arriving at the 70 percent figure, the construction of the board’s position by the majority would seem to violate the principle that public officials, acting officially, are entitled to a presumption that they have properly and accurately performed their duty until the contrary appears. State v. Ward, 172 Conn. 163, 171, 374 A.2d 168 (1976); Parham v. Warden, 172 Conn. 126, 134, 374 A.2d 137 (1976).
Because of the construction given the board’s position, the majority quite correctly concludes that where “the assertion of such discretionary authority conflicts with specific legislative mandates expressly providing *478a different result, the purported exercise of discretion is invalid.” The short answer to this principle, however, is that a construction of the board’s position as delineated above, which gives full effect to all of the statutory provisions, does not conflict with specific legislative mandates.
It is true that § 5 (a) does not delineate specific standards for the board to apply in exercising its discretion under the ordinance. In light of the statutory scheme, however, which mandates a floor, a ceiling and a “pension ladder” based upon additional years of service, the ordinance “ ‘establishes] primary standards’ ” and “ ‘lay[s] down an intelligible principle to which the administrative officer or body must conform.’ ” New Milford v. SCA Services of Connecticut, Inc., 174 Conn. 146, 149, 384 A.2d 337 (1977). “The duties of an administrative agency . . . necessarily include the right to exercise discretion .... In exercising that discretion, the factors to be taken into consideration ‘are not mechanical or self-defining standards,’ and, thus, wide areas of judgment are implied. Such discretion is the ‘lifeblood’ of the administrative process.” (Citations omitted.) Riley v. State Employees’ Retirement Commission, 178 Conn. 438, 442, 423 A.2d 87 (1979). Pension statutes have as their purpose “the promotion of the general welfare, and for that reason pension statutes are liberally construed to accomplish that objective.” 3 Sands, Sutherland Statutory Construction (4th Ed.) § 71.09. “[W]here power over a particular subject matter has been delegated to a municipal corporation by the legislature, without any express limitations, the extent to which that power shall be exercised rests in the discretion of the municipal authorities, and as long as it is exercised in good faith and for a municipal purpose the courts have no ground upon which to interfere.” 56 Am. Jur. 2d 286, Municipal Corporations *479§ 227. Indeed, this court has previously sanctioned a legislative grant of discretion without any discernible standards other than “such sums” “at such times” that the board “may deem advisable.” State ex rel. Kirby v. Board of Fire Commissioners, 129 Conn. 419, 426, 29 A.2d 452 (1942). Since this court has placed its imprimatur upon a delegation of discretion as unbridled as the phrase “may deem advisable,” it is difficult to understand why the “not less than” phrase, tempered as it is by the mandatory limitations of § 5 (a), should fail because of inadequate standards.
Undoubtedly, circumstances may arise where an administrative body, in exercising its discretion, will abuse that discretion. This possibility, however, should not, ipso facto, eliminate that discretion. In the present case the board listed several factors relating to the nature and commitment of Chief Howell’s service to the department as justification for exercising its discretion. “It is unrealistic to demand detailed standards which are impracticable.” Forest Construction Co. v. Planning & Zoning Commission, 155 Conn. 669, 679, 236 A.2d 917 (1967). The several criteria on which the board exercised its discretion in the present case clearly indicate the impracticability of limiting discretion to specific enumerated factors beyond the mandates of § 5 (a). The fact that this discretion could be abused is not a valid basis upon which to divest the board of such discretion. “In an appeal of this nature, it is neither our function nor that of the [trial court] to retry the case or to substitute our or its judgment for that of the defendant [board].” Riley v. State Employees’ Retirement Commission, supra, 441. There are, however, recognized principles upon which a court may vacate an award entered pursuant to the exercise of discretion: a showing that the entity acted illegally, arbitrarily, or in abuse of the discretion vested upon it. Id., 444.
*480Finally, the majority has failed to consider adequately the practical construction previously placed upon a similar act (insofar as the present issue is concerned) with reference to the retirement of the former chief. It is clear that such previous action by the board is entitled to some consideration in our construction of “what the law is.” Wilson v. West Haven, 142 Conn. 646, 657, 116 A.2d 420 (1955). Although the previous fire chief was retired under the provisions of a prior special act and not the home rule ordinance, it is undisputed that he received a pension at 70 percent of his preretirement salary. Because the first special act provided for retirement strictly at 50 percent of income, it is reasonable to infer that the prior chief could have received his pension only under the provisions of the 1967 special act, which contained the “at least” language, the mandatory pension ladder, and which the majority concedes is the functional equivalent to the present home rule ordinance.
The majority dismisses consideration of the prior practice because there were “few particulars” concerning the prior chiefs service with the fire department, thereby implying that he may have served for thirty-five years or more and that therefore no discretion was involved in that award. A careful reading of Alderman’s testimony, however, justifies the conclusion that both the prior chief, Johnson, and Chief Howell retired after thirty-one years of full-time employment with the fire department.5 Therefore the board must have exercised discretion in retiring the previous chief at 70 percent of his preretirement salary.6
*481Although the record does not reveal a statement of purpose behind the promulgation of the present ordinance, it is a reasonable assumption that its purpose is to encourage the continuation in service of experienced, dedicated personnel and to reward yeoman service via a discretionary additional sum. By its judicial excision of the “not less than” provision of the ordinance, the majority has effectively thwarted the board in its attempt to fulfill that purpose.
I would find error in the trial court’s judgment and remand the case with direction to render judgment for the defendant.
This omission of the phrase “not less than” takes on added significance when the legislative history of the ordinance is considered. As the majority opinion reveals, the first special act concerning fire department pensions provided simply a pension “equal to one-half of his regular monthly pay.” The act was subsequently amended to provide a pension “of at least one-half of his annual salary,” which the majority concedes is the functional equivalent of the present “not less than one-half” statutory language. Although the legislative history fails to provide insight as to the reason for the subsequent inclusion of “at least,” “amendments carry with them a presumption that they are effecting a change in the existing law.” Robinson v. Unemployment Security Board of Review, 181 Conn. 1, 21 n.6, 434 A.2d 293 (1980).
Alderman: “We took into consideration the part over 25 years, mainly the 6 percent, that we—the six years at 2 percent extra, but in reality, I think more than anything else, we took into consideration his service and what he had served.”
Alderman: “I think that we took into consideration what the prior Chief had done and the language of what we felt we could give Chief Howell, in the Home Rule Ordinance.”
A reasonable interpretation of this statement is that the board considered what it had done for the prior chief, i.e., extra compensation for meritorious service, and then applied to that amount a sum in accordance with the precise arithmetical formula contained within the Home Rule Ordinance.
Similarly, the trial court, in its memorandum of decision, relied on the board’s failure to follow the statutory formula in declaring the pension awarded Chief Howell to be null and void. Here again, I interpret the board’s action; see footnotes 2-3, supra; as a decision not to limit the award to the mandatory directives delineated within the ordinance so as to attain the maximum allowable pension consistent with the statutory scheme.
Alderman: “So, we felt that in total, he [Chief Howell] should be treated the same as the previous chief, William Johnson. That he should also be retired at 70 percent, considering he had also worked for thirty-one years for the Department.”
Furthermore, it is noted that in argument, when inquiry was made concerning the proposition of Wilson v. West Haven, 142 Conn. 646, 657, 116 *481A.2d 420 (1955), delineated above, counsel for the plaintiff, while not disputing that proposition, sought to distinguish the award to the former chief because that pension was awarded under the terms of a prior statute. This argument, however, is effectively rebutted by the fact that only the 1967 act authorized a pension beyond 50 percent of salary, and is, as the majority concedes, the functional equivalent of the present ordinance.