. . ." Barnes v. Ingram, 217 Tenn. 363, 397 S.W.2d 821, 825 (1965) (quoting Marshall Bruce Co. v. City of Nashville, 109 Tenn. 495, 71 S.W. 815, 819 (1903)); see also Faust v. Metro. Gov't of Nashville Davidson County, 206 S.W.3d 475, 485 (Tenn.Ct.App. 2006) (holding a reclassification of civilian employees to be outside the authority provided by the Metropolitan Code). The rationale for these principles is well-settled in the law:

1988)). Furthermore, "'[t]he provisions of the charter are mandatory, and must be obeyed by the city and its agents . . . .'" Allmand, 292 S.W.3d at 625 (quoting Barnes v. Ingram, 397 S.W.2d 821, 825 (Tenn. 1965) (in turn quoting Marshall & Bruce Co. v. City of Nashville, 71 S.W. 815, 819 (Tenn. 1903))).

We must construe together the portions of both the Charter and the Code of Ordinances dealing with the same subject matter. See 421 Corp. v. Metro. Gov't of Nashville and Davidson County, 36 S.W.3d 469 (Tenn. Ct. App. 2000); see also Barnes v. Ingram, 397 S.W.2d 821, 823 (Tenn. 1966) (construing the Charter and Ordinances together); Posey, 164 S.W.3d at 576-77 (same). Article 7, Section 53 of the City Charter vests the Board of Commissioners with authority to establish a retirement or pension system for the officers and employees of the Fire Department and the Police Department and to determine who may be included as members of such system.

"[T]he provisions of the charter are mandatory, and must be obeyed by the city and its agents. . . ." Barnes v. Ingram, 217 Tenn. 363, 373, 397 S.W.2d 821, 825 (1965). When a municipality fails to act within its charter or under applicable statutory authority, the action is ultra vires and void or voidable.