The opinion of the court was delivered by: Justice Harrison
Under the Illinois Plumbing License Law (225 ILCS 320/0.01 et seq. (West 1996)), lawn sprinkler systems can only be installed by licensed plumbers; licensed apprentice plumbers under the supervision of a licensed plumber; or, where a single family residence is involved, by the owner, owner occupant or lessee occupant of the residence. The issue in this case is whether that limitation is constitutional and can be enforced by the State to prevent a lawn sprinkler company from using unlicensed laborers to install the pipes and sprinkler heads in its lawn sprinkler systems where the system includes a backflow prevention device installed by a licensed plumber to prevent contamination of the water supply. The circuit court answered this question in the negative, holding that the limitation in the statute as applied in this case constitutes an "unreasonable interference with personal and property rights *** within the meaning of the State and Federal Constitutions." The State brought a direct appeal to this court under our Rule 302(a) (134 Ill. 2d R. 302(a)). We now reverse and remand.
The litigation before us commenced when the State filed suit in the circuit court of Du Page County to enjoin Daniel Cassidy and his business, KADC Corporation, d/b/a Sundance Irrigation (hereinafter referred to collectively as Cassidy), from using laborers rather than licensed plumbers to install the pipes and sprinkler heads in its lawn sprinkler systems. The basis for the State's suit was that the use of laborers violated the Illinois Plumbing License Law (225 ILCS 320/0.01 et seq. (West 1996)).
The Illinois Plumbing License Law mandates that "all plumbing shall be performed only by plumbers licensed under the provisions of this Act hereinafter called `licensed plumbers' and `licensed apprentice plumbers.' " 225 ILCS 320/3(1) (West 1996). As used in the statute, " `plumbing' means the actual installation, repair, maintenance, alteration or extension of a plumbing system by any person" and is defined to include "lawn sprinkler systems." 225 ILCS 320/2 (West 1996). Accordingly, the law in Illinois is that lawn sprinkler systems can only be installed by a licensed plumber or a licensed apprentice plumber. Where the work is done by a licensed apprentice plumber, the apprentice must be supervised by a licensed plumber. 225 ILCS 320/3(4)(a) (West 1996).
The statute recognizes an exception to these rules for the owner occupant or lessee occupant of a single family residence or the owner of a single family residence under construction for his or her occupancy. Such owner, owner occupant or lessee occupant is not prohibited
"from planning, installing, altering or repairing the plumbing system of such residence, provided that (i) such plumbing shall comply with the minimum standards for plumbing contained in the Illinois State Plumbing Code, and shall be subject to inspection by the Department or the local governmental unit if it retains a licensed plumber as an inspector; and (ii) such owner, owner occupant or lessee occupant shall not employ other than a plumber licensed pursuant to this Act to assist him or her." 225 ILCS 320/3(2) (West 1996).
The Illinois Plumbing License Act provides that persons violating the Act or a rule or regulation promulgated thereunder "shall be guilty of a Class B misdemeanor and a fine of $500 for the first offense; and a second or subsequent violation of this Act shall be guilty of a Class A misdemeanor with a fine of $1,000." 225 ILCS 320/29(1) (West 1996).
The State's Attorney of the county in which the violation occurred or the Attorney General, acting in the name of the People of the State of Illinois, are responsible for bringing enforcement actions. In such actions, the court may enjoin the use of plumbing installed in violation of the law or a rule or regulation promulgated thereunder until it has been corrected. 225 ILCS 320/29(1) (West 1996). In addition,
"[i]f it is established that the defendant contrary to this Act has been or is engaging in or about to engage in plumbing without having been issued a license or has been or is engaged in or is about to engage in plumbing after his or her license has been suspended or revoked or after his license has not been renewed, the Court may enter a judgment perpetually enjoining the defendant from further engaging in plumbing contrary to this Act. In case of violation of any injunction entered under this Section, the Court may summarily try and punish the offender for contempt of Court. Such injunction proceedings shall be in addition to, and not in lieu of, all penalties and other remedies in this Act provided." 225 ILCS 320/29(2) (West 1996).
In the matter before us, the State has not attempted to prosecute Cassidy for any past violations of the Plumbing License Law. It merely seeks to enjoin him from violating the statute in the future.
The State's enforcement action was originally commenced in the circuit court of Du Page County, but was subsequently transferred to Kane County, where Cassidy had brought a related action for injunctive and declaratory relief against the City of Aurora. The State and Cassidy each filed motions for summary judgment. 735 ILCS 5/2-1005 (West 1996). The materials presented to the circuit court in support of the parties' respective motions showed that Cassidy is in the business of designing and installing "lawn sprinkler systems" as that term is defined by section 2 of the Plumbing License Law (225 ILCS 320/2 (West 1996)).
Cassidy's lawn sprinkler systems consist of underground pipes and sprinkler heads connected to a customer's potable water supply by means of a reduced pressure zone backflow prevention device, known as an RPZ valve. RPZ valves are necessary because without them, changing pressure could pull contaminated water from a customer's lawn into the house's water supply. Among the type of contaminates that must be guarded against in a lawn sprinkler system are fertilizers, insects, pesticides, and fecal matter from animals.
When an RPZ valve is installed and operating properly, there is no threat of backflow contamination to the potable water supply. Cassidy always uses licensed plumbers to install the RPZ valves on his systems. That is not the case with every lawn sprinkler company. Some do not use licensed plumbers to install the valves, and some do not use the valves at all.
After considering the parties' respective positions, the circuit court ultimately granted Cassidy's motion for summary judgment and denied the motion for summary judgment filed by the State. The circuit court held that the Illinois Plumbing License Law was designed to guard "the public's right to a protected potable water supply, free of contamination resulting from inadequate installation procedures." In the court's view, this interest was adequately served by Cassidy's use of licensed plumbers to install RPZ valves on his lawn sprinkler systems. Once an RPZ has been properly installed, the court held, it constitutes "an absolute deterrent to the contamination of potable water within the system." Accordingly, the court believed that requiring Cassidy to also use licensed plumbers, rather than laborers, to install the pipes and sprinkler ...