Previously: What is law? - Part 4
The Judicial Branch is where the laws and regulations created by the legislative and executive branches make contact with the world at large. The most common way to think of the judiciary is as the public forum where sentences/fines for not abiding by the law are handed down and as the public forum where disputes between private parties can be adjudicated by a neutral third party. This is certainly a major part of it but it is also the place where law gets clarified with finer and finer detail over time, in USA-style and UK-style "common law" legal systems.
I like to think of the judicial branch as being a boundary determinator for legal matters. Any given incident e.g. a purported incident of illegal parking, brings with it a set of circumstances unique to that particular incident. Perhaps the circumstances in question are such that the illegal parking charge gets thrown out, perhaps not. Think of illegal parking as being – at the highest level – a straight line, splitting a two dimensional plane into two parts. Circumstances to the left of the line make the assertion of illegal parking true, circumstances to the right of the line make the assertion false.
In the vast majority of legal matters, the dividing line is not that simple. I think of the dividing line as a Koch Snowflake. The separation between legal and illegal start out as a simple Euclidian boundary but over time, the boundary becomes more and more complex as each new "probe" of the boundary (a case before the courts), more detail to the boundary is added. Simple put, the law is a fractal. Even if a boundary starts out as a simple line segment separating true/false, it can become more complex with every new case that comes to the courts. Moreover, between any two sets of circumstances for a case A and B, there are an infinity of circumstances that are in some sense, in between A and B. Thus an infinity of new data points that can be added between A and B over time.
Courts record their judgments in documents known collectively as “case law”. The most important thing about case law in our focus areas of USA-style and UK-style legal systems is that it is actually law. It is not just a housekeeping exercise, recording the activity of the courts. Each new piece of case law produced at time T, serves as an interpretation of the legal corpus at time T. That corpus consists of the Acts/Statutes in force, Regulations/Statutory Instruments in force *and* all other caselaw in force at time T. This is the legal concept of precedent, also known as stare decesis.
The courts strive, first and foremost, for consistency with precedents. A lot of weight is attached to arriving at judgements in new cases that are consistent with the judgements in previous cases. The importance of this cannot be over-estimated in understanding law from a computational perspective. Where is the true meaning of law to be found in common law jurisdictions? It is found in the case law! - not the Acts or the regulations/Statutory Instruments. If you are reading an Act or a regulation and are wondering what it actually means, the place to go is the case law. The case law, in a very real sense, is the place where the actual meaning of law is spelled out.
From a linguistics perspective you can think of this in terms of the pragmatics counterpart to grammar/syntax. Wittgenstein fans can think of it as “language is use”. i.e. the true meaning of language can be found in how it is actually used in the real world. Logical Positivists might think of it as a behaviorist approach to meaning. That is, meaning comes from behavior. To understand what a law means – watch what the courts interpret it to mean.
The meaning of the law comes from how it is used in practice and that use comes from the empirically observable behavior of the courts. I could be a staunch advocate of my interpretation of the law at time T as written in the Acts/Statutes and Regulations/SIs but if the caselaw supports a different interpretation to mine, I will have an uphill battle defending my interpretation in court.
There is a useful computing analogy here too. Every programmer knows that there are times when the quickest way to get to the true meaning of a piece of code is to run it and see what happens. In the world of law, the quickest way to get an understanding of the true meaning of some legislative material is to find how it has been treated in the case law. It is also a highly efficient way of getting to "truth" because, at the end of the day, it does not matter how many possible interpretations might be valid for any given point of law. What really matters is how the courts have interpreted it in the past.
Extending the programming analogy a little bit. It is often easier to figure out what some code does in a particular set of circumstances by looking for a unit test that matches the circumstances of interest. Extending the analogy even further, any new tests added should not invalidate the existing tests and any code changes to acommodate new circumstances should not invaldate any existing caselaw. In other words caselaw behaves a little like regression testing in software development. The courts strive to not "break" previous judgements.
It will come as no suprise that most lawyers place great importantance on caselaw searching. It might come as a suprise that there is no central entity that publishes the official caselaw. Typically courts act autonomously and publish their own volumes of caselaw periodically. Much of it, to this day, still on paper with the paper being the definitive source. I.e. if a court does produce paper plus electronic case law, the paper "wins" in the event of any discrepency.
There is a long history going back to at least the Nineteenth century of third parties acting as aggregators of caselaw. Mostly notably, West Publishing (now part of ThomsonReuters) and LexisNexis, now part of ReedElsevier. I think it is fair to say that the modern practice of law in common law jurisdictions would not be possible if practitioners did not have the ability to rapidly search caselaw.
The sheer volume of existing caselaw and the rate of creation of new caselaw is such that without computers, the common law system would not be able to function as it does today. Most of the computational support to date has been in the form of document production and search/retrieval. There are signs that that is changing now as machines start to help practitioners interpret the caselaw. This is a topic for another day!.
It is important to note that the corpus of caselaw is not purely accretive. Caselaw is, from time-to-time, repealed and practitioners need to be careful in citing caselaw to ensure that the cited caselaw is still considered "good law". Again, enter the computers and their search capabilities. In particular a ubiquitous legal term "shepardizing" which refers to looking up a case to find its status and find what other cases cite it and what other cases it also cites.
The fact that caselaw is not purely accretive creates yet another interesting “at time T” issue. Any judgement the courts might arrive at, at time T is necessarily contingent on the full corpus at time T. The exact same issue, examined at some future time point T+1 might produce a different result if some of the caselaw that was “good law” at time T is no longer “good law” at time T+1. We will return to this later on when we talk about defeasible logic and analogical reasoning but they are best parked for now until we have finished the survey of the sources of law itself.
It is in the area of caselaw that our imagined virtual legal reasoning box runs into its biggest challenge with respect to access to the raw materials of law. In common law jurisdictions, the volume of caselaw that is considered "good law" at any time T is vast, goes back centuries and is not available anywhere as a single corpus. Plus, the best sources are in fee-based repositories.
The good news is that the caselaw corpus is not homogenous in terms of its importance to precedent. In many interesting respects the caselaw corpus is the grand daddy of all Social Networks. Yes, you read that right. Social Networks! Cases are linked to other cases by means of a formal referencing mechanism. A commonly used set of standards for these citations is known as the Blue Book. The links between cases are not randomly distributed. They are in fact a poster child for the concept of a power law distribution.
Lawyers and judges working with the caselaw corpus spend their time on the subset of cases that naturally follows from following citations. Cases that that have high "rank" - where rank refers to the inbound and outboud connections to other cases – are very important cases, by virtue of the citation network around them. If this reminds you of the original Google concept of Page Rank you are exactly right. Citations serve two primary purposes. Firstly, they are indicative of the relative importance of a case (“how often has this case been cited positively in cases like mine?”) and secondly, they give a good indication of how robust a case is likely to be against repeal. The citation network can tell you a lot about the knock-on effect of repeal and remember, in common law systems, a really important "logic" at work is the logic of consistency with previous decisions.
There is an old adage that it is not possible to step into the same river twice. This adage capture my mental model of caselaw. It is like a fast flowing river with the added twist that over time, it can forge new pathways and route around obstacles, while continuing to be "the same" river. In fact, the entire corpus of law is like that. It is constantly changing – every day. Every new piece of caselaw, every new regulation, every new act, adds new data points into the fractal geometry of the previously mentioned Koch Snowflake of legality.
Rivers are not easy things to capture in databases! That is why, to my mind , the key challenge in regulatory data management is actually regulatory change management. In fact, I think of the two as being the same thing. Modelling the data is hard enough - as I hope you can appreciate based on the material presented here so far. Modelling how the data changes and how any computational system can be kept up to date with the changes, is another matter completely. Regulatory change is not something you can afford to park and deal with another day in any useful conceptual model of law. I would argue it needs to be the central plank of the data model of law. After all, if you have a model that works well when things change, it will work just fine when things do not change. But the reverse is not true.
So that is it for caselaw for now.
Next up, we wrap up coverage of the sources of law with some other sources not yet mentioned. We will also take a stab at summarising and classifying the issues related to accessing the corpus of law, covering all the sources mentioned.
From there, we will turn our attention to the legal reasoning process itself. That is where the fun stuff really starts. See What is Law - Part 6.