SPECIAL LAW

           A special law, sometimes called a “private law” or a “local law,” refers to a law that applies only to a specific group of people or an organization. In this way it is different from general law, which applies to everyone under the jurisdiction of the elected body that made the law. For example, the crime of murder is a general law. A special law can be drafted to address concerns or needs of a particular locality within a larger region or a specific institution or government entity.
           The uses of special law are many and varied. Special laws often involve important issues dealing with social institutions. They can be enacted to fund or replenish pensions for government employees such as police, firefighters, and educators. They are often used to authorize emergency money for hospitals or highway departments that was not in their original budgets.
           They are also important in the areas of industry regulation and environmental issues. They made add additional burdens to a specific industry or give incentives for doing things that will have a positive impact on the environment or general public health. With ever-increasing populations and expansion, municipal annexations are also a subject of special law.
           Many jurisdictions do not allow the use of special law where an existing general law could apply. Some states severely restrict the use of special law in their constitutions. In general, these provisions were originally drafted to make sure that the legislature did not pass too many laws or devote too much time to local issues instead of those affecting a large region or the entire state. Some legislatures attempt to balance these concerns by allowing the use of special laws only in areas of medium to large populations.
           With the many laws now in existence, it can sometimes be difficult to decide whether a special law is really necessary in a particular case, which is when it can be helpful to look at the historical reasons for limiting special laws. One of the fears about special laws was that powerful people, including those who made the law, could use it for selfish ends. Another was that they could be used to oppress classes of people who were held in disfavor. If a special law serves a real need, it is meant to hold off some social harm or address a specific social ill; there is no concern about selfish interests. If the law’s intent is to promote the public good in some way that a general law cannot, then it is usually considered necessary.
Source:  http://www.wisegeek.com/what-is-a-special-law.htm