How deterministic are modern legal systems? I am a software engineer trying to understand how judges make decisions in lawsuits. In computer and other sciences there is a concept of deterministic system: In mathematics and physics, a deterministic system is a system in which no randomness is involved in the development of future states of the system. A deterministic model will thus always produce the same output from a given starting condition or initial state. In lay terms this simply means that if the system is being fed the same input again and again it will generate exactly the same output each time. If applied to legal system: Each judge would be a sub-system that builds the whole US legal system Evidence provided to the judge under lawsuit would be one kind of the input Ruling made by the judge would be the the output of the lawsuit Lawsuit would be a test to see how legal system reacts on particular input Here are my questions (if you feel comfortable answering only some of these questions I would still appreciate it): How deterministic is the US legal system? Can you provide examples of popular lawsuit instances that were almost the same but resulted in very different outcome? And If you are familiar with the steps that lawsuit has to go through in the US legal system, then what are these steps (e.g. assigning a random judge to a lawsuit; same judge unpredictably deciding what is and what isn't convincing evidence to him; same judge deciding how much of punishment to give for each violation under same circumstances ...). How much unpredictability does each step introduce and what is the typical source of that unpredictability? And What are efforts to make the legal system more deterministic (e.g., let computers to contribute to ruling, precedent-court ...)? Are persons involved in the judicial system concerned about this problem, and does it have a term in the legal world? Also, I understand that this question is quite general and does not specify some of the variables that could affect answers (e.g. country or state, type of lawsuit). You can chose how to answer it.
How deterministic is the legal system? It depends. And less than we might wish. It depends on the case. How complex is the fact pattern? How strong is the evidence? How clear is the law? How compelling are the legal precedents? Questions of that nature. The only generalization I might make would be that "lower level" cases seem more deterministic than "higher level" cases. By higher level, I mean those heard by a supreme court making constitutional decisions. Here is a web site that has created a prediction market out of supreme court cases. Many have written on this topic. Read this answer. It is an excellent treatise on the subjectivity of the legal system. Written by a real attorney. Read this answer too. My advice: If you seek a deterministic system, don't look to the legal one.
The concept of &quot;ignorance&quot; of laws isn't about the individual. It's about administratibility of the system. The argument is that a system with a wide-ranging ignorance defense would struggle to produce results—just or otherwise. So the American system presumes knowledge of the law and then carves out narrower exceptions, such as mistake of law. For example, the law wasn't published, or it had been overruled. Alas, the question about why there isn't a hotline belongs on another site.
It is purely ceremonial. The tendency in modern jurisprudence is towards the practical and away from legalisms and technicalities. Even if a judge used a gavel in some way inappropriately, it would be unlikely to have any legal significance for anyone but the judge. An argument based on gavel misuse would fall into the &quot;fringe-on-the-flag&quot; category of legal arguments (yes, there are people who think that the court's powers are determined entirely by the fringe on the courhouse flag). The gavel is a traditional trapping of a common law courtroom, but has no legal significance.
While this isn't a simple and direct answer, it should point you in the right direction. There are countries which like the United States have parallel national and subnational court system, including Australia, Belgium, Brazil, Canada, Ethiopia, Germany, India, Mexico, Nigeria, South Africa, Spain, and Switzerland. Different rules of procedure for different courts within a larger overall court system for a federal jurisdiction are not that unusual even in nominally unitary court systems. But, the division between them is on something of a continuum with fine shades of differences between them. Only a few are as close to the extreme of power sharing and a &quot;federalist&quot; approach as the United States, however. Also even unitary court systems (in a geographic and federalism sense) often have parallel court systems on subject matter grounds. For example, France has both ordinary civil courts and labor courts whose rulings could overlap, and England historically had courts of law and courts of equity with a complex relationship to each other (and also ecclesiastical courts with jurisdiction of matters now vested in the civil courts of law like inheritance of tangible personal property). Similarly, Northern Ireland has or has had what amount to different parallel legal systems for terrorism and non-terrorism criminal offense. Most countries also have parallel criminal and quasi-criminal legal systems for civilians and soldiers respectively. I've seen this tension between the two systems as a plot point in contemporary English police procedural dramas, for example. On the other hand, systems with a more unitary legal system rarely are so fierce in their defense of protections against double jeopardy as the United States, and the dual sovereignty doctrine in U.S. double jeopardy law can be seen as a safety valve in practice and as applied in cases where the double jeopardy rule as interpreted under the U.S. Constitution is too strong a bar to legitimate second prosecutions. A comparative analysis of double jeopardy concepts can be found here. It is tricky to reduce the subtly differences between the rules in different countries to a clear yes or no kind of answer. A square answer to your question requires detailed examination of a dozen or more court systems that someone felt the need to write a book about to explain. If I can find a more specific answer I will update this one.
So my understanding is that the phrase "common law" can refer to either the concept of laws established by court precedent or it can refer to a specific body of laws that have been established that way. Yes. Should I just be inferring that from context? Yes. Is there a single body of "common law"? No. Are there distinct bodies of "U.K. common law" and "U.S. common law" for example? Yes, furthermore there is different common law in England/Wales, Northern Ireland &amp; Scotland and each state of the US. Further, Scotland and Louisiana are not straightforward common law jurisdictions but rather a blend of common and civil law. If so, how are they related? They are related in that they all: have a common source, middle English common law evolve in the same way - judges interpreting the current common law and the statutes of the legislature follow an appeals system through higher levels of courts. They do not all go in the same direction though. Do judges in common law countries cite court decisions in other common law countries? Sometimes; it depends on the "distance" of the other jurisdiction. A judge in New South Wales is quite likely to consider how judges in Queensland and Victoria have considered similar laws, less likely to look at the UK and Canada and extremely unlikely to look at the USA. This has a lot to do with how far back it is since the "last common ancestor" of the law; the longer the corpus of law has been separated the more likely that the principles have diverged, partly this is cultural drift but mostly this is differences in statutes that actively modify the common law. Usually, jurisdictions within the same country are quite close to each other; partly due to common culture but often because of a genuine effort to "harmonise" laws across borders. There are occasions, however, where legislatures "steal" laws from other jurisdictions, in which case they often look to each other for early development of common law on those laws. For example, the Alberta (Canada) Builder's Lien Act 2000 and the NSW (Australia) Building and Construction Industry Security of Payment Act 1999 both address the same "wrong" and both had a common and parallel genesis pre-enactment; early cases in each jurisdiction were watched by the other.
The phrase "reasonable doubt" was formed hundreds of years ago, and does not hold any mathematical or probabilistic meaning. It is for each individual juror to decide for themselves what constitutes "reasonable doubt", and whether the evidence presented to them has crossed that threshold. EDIT for extra clarity: As stated above, the definition of "reasonable doubt" is intentionally vague*, and left to be decided by each juror for themselves on a case by case basis; as such there is no single rule that can be applied to jurors (also note barring accepting a bribe, a juror cannot be legally sanctioned for their conduct as a juror, nor their vote, regardless of the evidence before them). So one juror might judge by P(A|B), another might judge by the defendant's appearance, another might judge by the majority of their peers (so that they can go to a ball game that evening, such as in the film 12 Angry Men), another might disagree with the law (see: jury nullification) and so vote not guilty on that basis, and another might bow to social pressure and convict despite overwhelming evidence that the defendant is not guilty (for example, at the end of To Kill A Mockingbird). A prosecutor cares about convincing the entire jury that the defendant is guilty(outside of Oregon and Louisiana, where only 10/12 vote is needed to convict, so the prosecutor only cares convincing 10 jurors). The defense only cares about convincing a single juror (or three in LA or OR), although more can be useful to prevent a mistrial. The defense (in theory) should not care whether or not the defendant is guilty. *The origin of reasonable doubt was in Britain, where certain jurors would refuse to convict, despite any evidence, due to religious prohibitions of "Judge not, less ye be judged".
The legal system advances practitioners on a number of criteria, not all of which relate to their legal education. It's essentially the same for all professions - your schooling/education may or may not determine your success in the field. Also relevant would be the social circles you navigate, your achievements post-education, and so on.
U.S. answer only. Are there a few database-like resources that would allow me to easily search for such cases? It is balkanized. It also isn't entirely clear what information about the cases interests you. Almost all federal court filings (but not administrative law decisions) are in a database called PACER. Each state has its own system. Some are almost completely unified, and in others, there are many databases. In Colorado, for example, the Colorado E-Filing system has all filings in state courts, but courts outside the state court system, mostly the Denver County Court and municipal courts, as well as some major private arbitration firms, are on their own and most subcontract the job to a division of LexisNexis, a private firm. In both cases, access to these filings is not free except to parties, and has lots of data with access restricted to parties and the court. Published appellate court decisions are also available at an Internet based source. None of these covers administrative law decisions in Colorado, however. Administrative law decisions are usually kept by the agency and also often by a commercial firm that compiles them. Some of them do not give the public access to the decisions in the absence of a FOIA or open records act request. Commercial firms like Westlaw and LexisNexis and several less well known firms (including a free one run by Cornell University), keep databases of published decisions of appellate courts plus a somewhat random assortment of unpublished decisions, with federal court trial court decisions getting much more heavy coverage than state court trial decisions and unpublished state appellate court decisions. But, these are only key court orders, not all filings in the case, and are not the true source documents. There is also a non-profit consortium that maintains a database of court records from the 75 most populous counties in the United States, and there is a private firm that keeps selective track of jury verdicts to the fullest extent that it can obtain them. Some credit reporting agencies (both consumer credit and business credit agencies) maintain databases of judgments and liens.