HAMILTON, J.

This appeal concerns the constitutionality of Laws of 1975, 1st Ex. Sess., ch. 281, p. 1208 (RCW 46.52.118-.1198), an act relating to the towing or removing of motor vehicles from private property.

Chapter 281 was to become effective on September 8, 1975. Prior to its effective date, respondents, Crane Towing, Inc., and Washington Tow Truck Association, Inc., brought this action seeking a judgment declaring chapter 281 unconstitutional. A preliminary injunction was entered restraining and enjoining appellants, the Attorney General and the State of Washington, from enforcing or implementing chapter 281 during the pendency of the trial. On November 24, 1975, the trial court entered an order granting respondents' motion for summary judgment finding chapter 281 unconstitutional in its entirety. Appellants have appealed from this order claiming that chapter 281 is constitutional under the police powers of the State. Respondents have cross-appealed from the trial court's denial of their motion for attorney fees. We find chapter 281 constitutional, and accordingly reverse the trial court's order granting respondents' motion for summary judgment. We affirm the trial court's denial of respondents' motion for attorney fees.

Chapter 281 is a comprehensive, regulatory scheme governing private property owners and towing firms who tow or remove motor vehicles from private property. The act requires private property owners to post a sign on or near their property, which informs vehicle operators that unauthorized vehicles will be removed. The sign must also contain sufficient information to assist the vehicle operator or owner in the prompt recovery of his vehicle once it has been removed. RCW 46.52.1192. If the property owner does not post such a sign and has a vehicle removed from his property, the owner or operator of the removed vehicle is authorized to bring an action seeking recovery of his consequential and incidental damages arising from the interference with his ownership or use of the vehicle. RCW 46.52.1198.

Overriding these sections regulating private property owners are two important exceptions to the requirement that a sign be posted on or near the property.

First, the requirement of posting a sign does not apply to persons who possess or control "family residential property". RCW 46.52.1192; see RCW 46.52.119. This means an owner or occupier of "family residential property" is not subject to a suit by the owner or operator of the removed vehicle even when no sign is posted.

Second, any person who possesses or controls real property may have an "abandoned vehicle" towed or removed from his property without posting a sign and without the possible sanction of an action being brought against him by the owner or operator of the "abandoned vehicle". RCW 46.52.118. An "abandoned vehicle" is defined as:

[A]ny vehicle left . . . upon the property of another without the consent of the owner of such property for a period of twenty-four hours, or longer except that a vehicle shall not be considered abandoned if its owner or operator is unable to remove it from the place where it is located and so notifies law enforcement officials and requests assistance.

RCW 46.52.102.

This second exception greatly ameliorates the requirement that a person who does not possess or control "family residential property" must post a sign before removing vehicles from his property. If such a person does not wish to post a sign, he is not permanently barred from having the unauthorized vehicle removed, since that vehicle becomes an abandoned vehicle after 24 hours and subject to immediate removal without restriction.

Chapter 281 also imposes certain requirements on towing firms which remove vehicles pursuant to RCW 46.52.119 or RCW 46.52.1192. If the towing firm assesses a fee according to the number of miles a vehicle is towed, the towing firm can recover no more than the fees that would accrue for towing to the nearest storage location of any towing firm. The towing firm must also maintain personnel able and authorized to release vehicles on a 24-hour basis and must give notice of the removal to certain law enforcement agencies and to the registered owner of the vehicle. See RCW 46.52.1194.

In releasing vehicles, the towing firm is required to accept presentation of commercially reasonable tender sufficient to cover the costs of towing, storage, and other services. Commercially reasonable tender is defined in the act to include personal checks drawn on local banks with proper identification, and valid and appropriate credit cards. RCW 46.52.1196. In addition, if the owner or operator of the removed vehicle can provide adequate proof of his financial responsibility, employment and residence in the community, the vehicle must be released without payment with the understanding that the towing firm's costs will be paid within 30 days or shall be recoverable through an action at law. RCW 46.52.1196. If the towing firm does not comply with the requirements of RCW 46.52.1194 or .1196, the owner or operator of the removed vehicle may sue the towing firm for recovery of his consequential and incidental damages arising from the interference with his ownership or use of the vehicle. RCW 46.52.1198.

[1, 2] Appellants claim chapter 281 is constitutional as a proper exercise of the State's police power. Our role in testing the constitutionality of an act under the police power of the State was set forth in State v. Conifer Enterprises, Inc., 82 Wn.2d 94, 96-97, 508 P.2d 149 (1973), and bears repeating here.

Two steps are involved in measuring the constitutionality of a legislative enactment against the permissible bounds of the police power. First, does it tend to promote the health, peace, morals, education, good order and welfare of the people? More specifically, does it tend to correct some evil or promote some interest of the state? Shea v. Olson, 185 Wn. 143, 53 P.2d 615 (1936); Clark v. Dwyer, 56 Wn.2d 425, 353 P.2d 941 (1960), cert. denied, 364 U.S. 932 (1961). If the answer is yes, the wisdom, necessity and policy of the law are solely within the jurisdiction of the legislature. State v. Bowen Co., 86 Wn. 23, 149 P. 330 (1915); Reesman v. State, 74 Wn.2d 646, 445 P.2d 1004 (1968).

The second inquiry, more narrow, but equally important, is whether the particular statute under scrutiny bears a reasonable and substantial relation to accomplishing the purpose established in step one. Markham Advertising Co. v. State, 73 Wn.2d 405, 439 P.2d 248 (1968); Lenci v. Seattle, 63 Wn.2d 664, 388 P.2d 926 (1964).

These tests cannot be applied in a vacuum. The state interest to be promoted or the evil to be corrected, and the relationship of the statute to this purpose, must be sought out. However, in a state where legislative intent is seldom recorded, and where only infrequently does a legislative act carry a recital of facts upon which the legislature is acting, the court necessarily has had to engage in certain presumptions.

The basic rule is that if the court can reasonably conceive of a state of facts to exist which justify the legislation, those facts will be presumed to exist. Further, it will be presumed that the statute was passed with reference to those facts. State v. Laitinen, 77 Wn.2d 130, 459 P.2d 789 (1969); Markham Advertising Co. v. State, supra; Shea v. Olson, supra.

In addition to that presumption, the court is guided by two other rules. First, the burden of establishing the invalidity rests heavily upon the party challenging constitutionality. Second, every presumption will be in favor of constitutionality. Lenci v. Seattle, supra.

These rules are more than mere rules of judicial convenience. They mark the line of demarcation between legislative and judicial functions.

[3] Applying these tests to the legislation here, we think a set of facts conceivably exists which support a finding that chapter 281 tends to promote the safety and welfare of the people. Modern society's dependence on the automobile as the primary mode of travel is well known in this time of national discussion on energy conservation. Traveling hundreds of miles from one's home and back in 1 day, whether for business or pleasure, is surely not an uncommon experience. It cannot be doubted that the unexpected loss of the use of one's vehicle directly affects the safety and welfare of vehicle operators and owners. A person may be stranded hundreds of miles from home with no alternative mode of return travel and with no place to stay until the vehicle can be recovered. Similarly, the loss of the use of one's vehicle may substantially affect one's employment. Legislation which tends to assist members of the public from involuntarily losing the use of their vehicles and which tends to expedite recovery of their vehicles once they have been removed fairly and clearly promotes the safety and welfare of the public.

Further, chapter 281 bears a reasonable and substantial relation to accomplishing this objective of assisting vehicle operators and owners. Again, it must be kept in mind that a broad discretion is vested in the legislature to determine what the public demands and what measures are necessary to protect the public interest. Reesman v. State, 74 Wn.2d 646, 650, 445 P.2d 1004 (1968). Requiring property owners to post a sign warning vehicle operators that unauthorized vehicles will be removed is reasonably related to assisting members of the public from involuntarily parting with their vehicles if they should park their vehicles where they are not supposed to park them. Although respondents seek to characterize all trespassing vehicle operators as intentional wrongdoers, this may not always be true. A vehicle operator may assume he has permission to park on private property, either because of his prior conduct or because he sees other private vehicles parked in the parking lot of a business which has closed for the night. Thus, he may believe the private property owner has no objections to others using his parking lot after business hours. If a private property owner does not wish to have others use his property for parking, he need only post a sign. Similarly, because the sign must contain information regarding where the vehicle will be towed, this requirement also assists the operator or owner in retrieving his vehicle once it has been removed.

The requirements that the towing firm maintain personnel on a 24-hour basis who are authorized to release vehicles and that the towing firm accept commercially reasonable tender are also designed to facilitate retrieval of vehicles which have been removed. Again, these requirements undoubtedly bear a reasonable relation to the objective of rejoining the owner or operator with his vehicle once they have become separated.

Respondents argue that RCW 46.52.1198 must be held unconstitutional as an improper exercise of the police power because it is not reasonably and substantially related to the purpose of insuring compliance with the other sections of chapter 281. Respondents interpret RCW 46.52.1198 as allowing the owner or operator of a removed vehicle to sue the towing firm if the property owner does not comply with chapter 281 and also as allowing the owner or operator to sue the property owner if the towing firm does not comply with the chapter. In other words, respondents interpret RCW 46.52.1198 as authorizing the owner or operator of the removed vehicle to sue either the towing firm or the property owner regardless of fault. Although appellants obviously do not believe respondents' interpretation of RCW 46.52.1198 renders that section unconstitutional, appellants apparently agree with respondents' interpretation of that section.

[4, 5] Clearly, RCW 46.52.1198 was enacted by the legislature to insure compliance with chapter 281 by towing firms and property owners. If we were to interpret RCW 46.52.1198 as allowing liability without fault, we would agree with respondents that that section would not be reasonably and substantially related to the objective of insuring compliance with the other sections of chapter 281, and thus would not be a proper exercise of the police power. However, RCW 46.52.1198 can also be interpreted as only permitting an action against the party whose interference with the use or ownership of the vehicle was not in compliance with chapter 281. RCW 46.52.1198 authorizes owners or operators of the removed vehicle to sue "for consequential and incidental damages arising from any interference . . . which does not comply with the requirements of RCW 46.52.1192, 46.52.1194, and 46.52.1196." (Italics ours.) The words "arising from" are synonymous with the words "resulting from". See Roget's Int'l Thesaurus 72 (3d ed. 1962). Thus, RCW 46.52.1198 requires some causal connection between the damages suffered and the interference which does not comply with the other sections of

chapter 281. Because RCW 46.52.1198 is subject to two interpretations, one constitutional and the other unconstitutional, we presume the legislature intended a meaning consistent with the constitutionality of its enactment. Treffry v. Taylor, 67 Wn.2d 487, 408 P.2d 269 (1965); Martin v. Aleinikoff, 63 Wn.2d 842, 389 P.2d 422 (1964).

[6] Although we find that chapter 281 is a proper exercise of the State's police power, our inquiry cannot end here for if the act violates any specific constitutional rights guaranteed respondents, the act cannot stand. Peterson v. Hagan, 56 Wn.2d 48, 351 P.2d 127 (1960); State ex rel. Livingston v. Ayer, 23 Wn.2d 578, 161 P.2d 429 (1945); Shea v. Olson, 185 Wn. 143, 53 P.2d 615, 111 A.L.R. 998 (1936).

[7] Initially, we are confronted with respondents' arguments that chapter 281 infringes upon certain constitutional rights of private property owners. Respondents did not allege in their complaint nor did they introduce any evidence at trial that they are private property owners who would suffer from the requirements of RCW 46.52.119 and .1192. It has long been the rule in Washington that a plaintiff seeking a judgment declaring a statute unconstitutional must show that enforcement of the statute will directly affect him. DeGrief v. Seattle, 50 Wn.2d 1, 13, 297 P.2d 940 (1956); DeCano v. State, 7 Wn.2d 613, 110 P.2d 627 (1941). The rationale for this rule is quite simple. If a plaintiff is not directly affected by the enforcement of a statute, the declaratory judgment action becomes, in effect, an advisory opinion because of the lack of the necessary adversarial atmosphere. Respondents attempted to circumvent this deficiency by bringing their action on behalf of the people of the State of Washington. Simply stating the action is brought on behalf of all people of the State of Washington does not produce that element of conflict necessary to elevate the decision from being merely an advisory opinion on the constitutional rights of private property owners. See, e.g., State v. Grabinski, 33 Wn.2d 603, 612, 206 P.2d 1022 (1949). A plaintiff whose constitutional rights as a private property owner are allegedly infringed upon must be a named party to the action before these possible infringements can be reviewed.

Although respondents lack standing to raise the possible violations of constitutional rights of private property owners, the trial court also found chapter 281 violates several of respondents' constitutional rights as owners and operators of towing firms, which we will now review.

[8, 9] Respondents first argue that RCW 46.52.1194(1)(e), which limits the fee a towing firm may collect if the towing firm assesses a fee according to the number of miles a vehicle is towed, is unconstitutional as a deprivation of property without due process of law. It is difficult to comprehend how respondents are deprived of any property by this limitation. RCW 46.52.1194(1)(e) does not require towing firms to assess their fees according to the number of miles a vehicle is towed nor is there any limitation on the amount per mile a towing firm may charge. Thus, there is no deprivation of property.

Respondents also assert that RCW 46.52.1194(1)(e) impairs existing contracts which towing firms have entered into with private property owners in violation of U.S. Const. art. 1, § 10 and Const. art. 1, § 23. This contention must fail for two reasons. First, respondents did not place into evidence any contracts which this section supposedly impairs. Thus, any determination on this argument necessarily requires us to speculate as to whether RCW 46.52.1194(1)(e) in fact impairs any contract rights. Second, and more importantly, it is well established that parties cannot complain of an impairment of their contract rights when this impairment comes about through the State acting within its police power for the health, welfare, and good of the general public. It is presumed that parties contract with knowledge that reservation of essential attributes of sovereign power is written into all contracts as a postulate of the legal order. Veix v. Sixth Ward Bldg. Loan Ass'n, 310 U.S. 32, 38-39, 84 L.Ed. 1061, 60 S.Ct. 792 (1940); Aetna Life Ins. Co. v. Washington Life Disability Ins. Guar. Ass'n, 83 Wn.2d 523, 539, 520 P.2d 162 (1974).

[10] Respondents next argue that RCW 46.52.1196, which requires towing firms to accept commercially reasonable tender and in some instances release a vehicle without payment so long as it is understood that payment will be forthcoming within 30 days, denies them equal protection of the laws. The guaranty of equal protection of the laws and the prohibition against special privileges and immunities require that class legislation apply alike to all persons within a class and that reasonable grounds exist for making a distinction between those within and those without a specified class. Haddenham v. State, 87 Wn.2d 145, 550 P.2d 9 (1976); Seattle v. See, 67 Wn.2d 475, 408 P.2d 262 (1965), rev'd on other grounds, 387 U.S. 541, 18 L.Ed.2d 943, 87 S.Ct. 1737 (1967).

Although it is probably safe to assume that most businesses do accept commercial tender other than cash and that many extend credit for periods of 30 days or longer, it would appear that towing firms are the only businesses singled out by the legislature that are required to do so. The question then becomes whether there is a reasonable basis for requiring towing firms to accept commercially reasonable tender and extend credit.

We take notice of the fact that prior to this act most towing firms accepted cash only to cover all of their services before releasing the vehicle. The rationale for requiring cash only is quite elementary. The towing firm and the vehicle operator or owner have entered into this arrangement involuntarily. This relationship is instigated by a third party, the property owner, who wishes to have the vehicle removed. Generally, the owner or operator of the vehicle is not happy that his car has been towed away. Once his car has been returned he has no incentive to pay the towing firm for its unwanted and unrequested services which have not benefited the owner or operator. Thus, to insure collection of its fees, the towing firm required cash before giving up the car.

The reasons for requiring towing firms to accept commercially reasonable tender and to release vehicles without prior payment in certain instances are also quite clear. Because the relationship between the towing firm and the vehicle operator or owner is involuntarily created, the vehicle operator or owner has no advance warning of the towing firm services for which he will have to pay. Many times he may not have the cash available in order to retrieve his vehicle, especially in this day and age where individuals rely to a great extent on credit cards or acceptance of their personal checks for their day-to-day commercial transactions. Further, oftentimes the owner or operator learns his vehicle has been removed after business hours when it could be extremely difficult to obtain cash sufficient to retrieve his vehicle. This may be especially burdensome if the vehicle is removed on a Friday night when the owner or operator may have to wait until banks open on Monday morning before he can garner the necessary funds in cash. Of course, all the while his vehicle remains with the towing firm, and storage fees are increasing. If the owner or operator is in a distant city, this compounds the problem since alternative modes of transportation home may not be available and a place to stay may not be available for the owner or operator until he can retrieve his vehicle. [11] Although we recognize the burdens placed on a towing firm by requiring it to accept commercially reasonable tender other than cash and to extend credit, it must be stressed here that the legislature is dealing with a somewhat unique situation. Because of society's great dependence on private vehicles and the obvious dangers which may arise when a person is unexpectedly separated from his vehicle, coupled with the safeguards found in RCW 46.52.1196 to facilitate collection in the event of nonpayment, we believe reasonable grounds do exist for requiring towing firms to accept commercially reasonable tender and to extend credit in certain instances. Therefore, we find that RCW 46.52.1196 does not violate respondents' equal protection rights.

We find no merit in respondents' remaining arguments for upholding the trial court's decision. Because we find chapter 281 to be a valid exercise of the State's police power and find that chapter 281 does not impermissibly infringe upon respondents' constitutional rights, we reverse the judgment of the trial court declaring chapter 281 unconstitutional.

[12, 13] With respect to respondents' motion for attorney fees, we are satisfied the trial court correctly denied respondents' motion. It has long been recognized in this jurisdiction that attorney fees may be recovered only when authorized by a private agreement of the parties, a statute, or a recognized ground of equity. Hsu Ying Li v. Tang, 87 Wn.2d 796, 557 P.2d 342 (1976); State ex rel. Macri v. Bremerton, 8 Wn.2d 93, 111 P.2d 612 (1941). No statute or private agreement authorizing attorney fees exists in this case. Respondents suggest that attorney fees should be awarded here under either the "common fund" doctrine, see Weiss v. Bruno, 83 Wn.2d 911, 523 P.2d 915 (1974); Peoples Nat'l Bank v. Jarvis, 58 Wn.2d 627, 364 P.2d 436 (1961), or the "private attorney general" doctrine. As the name implies, the "common fund" doctrine requires the prevailing party to have brought suit to preserve or protect a fund which benefits the party and others. Even if respondents had prevailed here, no fund exists out of which attorney fees might be granted. As for the "private attorney general" doctrine, we have not extended that doctrine beyond its application in a "common fund" situation. See Swift v. Island County, 87 Wn.2d 348, 362-63, 552 P.2d 175 (1976). This present case does not lend itself to considerations of extending the doctrine.

The trial court's denial of respondents' motion for attorney fees is affirmed.

WRIGHT, C.J., and ROSELLINI, STAFFORD, UTTER, BRACHTENBACH, HOROWITZ, DOLLIVER, and HICKS, JJ., concur.