Local laws are, in essence, laws that are made that effect a very limited area geographically. Local laws can vary in scope, varying with how one decides to quantifying Most definitions of local law would almost be synonymous with municipal law, meaning related to a town or city. (judicial review), meaning it must adhere to overarching legal standards, up to an including the Constitution.
Local law is the category of legal research that relies predominantly on primary source research comparative to all others, since the scope often precludes there being an abundance of secondary research from which to draw. Naturally, because of their limited scope, many local laws are less likely to produce written material in reference to the law as a something like a Constitutional Amendment would.
For example, if an attorney was making a case that a local town ordinance was unconstitutional under the Second Amendment (The right to keep and bear arms)
Therefore, cases and arguments that are based on local laws often have to base their arguments more so on practical argument of the written law, than other arguments or opinions pertaining to that law.
Based on the scope of the law, the means by which it can be made available for public perusal can vary. In some cases, they will not be published at all, save for online, and online publication This means that finding the law in question, despite its specific nature, many involve field work or outsourcing of paralegal work in order to obtain the letter of the law, which will always be available at the local city hall or municipal courthouse, if there is one.
Finding secondary sources, if there are any, can be more difficult as well, since there will likely be very little, if any. Therefore, legal research will often have to be done in the interest of finding similar work, meaning that secondary work will almost always have to rely on digests, which primarily work on the basic of subject or key word.