Are there any situations where SCOTUS is required as first step? As far as I know, when the cases are heard by Federal judiciary, they are first heard by lower level courts, and only get escalated to SCOTUS once appealed from a ruling by a circuit court. Is that the case for 100% of cases? Or are there any situations where SCOTUS is required as first step (either Constitutionally or by statute)?
Short answer: Yes. There are some matters in the exclusive original jurisdiction of the U.S. Supreme Court, which consists of suits between U.S. states and/or foreign states with each other and suits involving diplomats. On average, one or two such suits are filed each year. The original jurisdiction in these cases is created by Article III of the United States Constitution (Section 2, Clause 2), and is exclusive in these cases by virtue of the 1789 Judiciary Act. The 11th Amendment also plays a role in this analysis. Long answer: The original jurisdiction of the U.S. Supreme Court is set forth in Article III, Section 2, Clause 2 of the United State Constitution, which states: In all cases affecting ambassadors, other public ministers and consuls, and those in which a state shall be party, the Supreme Court shall have original jurisdiction. In all the other cases before mentioned, the Supreme Court shall have appellate jurisdiction, both as to law and fact, with such exceptions, and under such regulations as the Congress shall make. Basically, these are cases of a state against the United States and/or another state, often regarding boundary disputes, interpretations of interstate compacts, or water rights, or cases involving diplomats adjudicating the extent of diplomatic immunity. (Incidentally, almost all, but not all of the cases in the U.S. Supreme Court's appellate jurisdiction are discretionary, but appeals to the U.S. Supreme Court from three judge panels ruling in certain election law cases are of right.) How rare are these suit in the original jurisdiction of the U.S. Supreme Court? On average, the U.S. Supreme Court has considered about one per year on the merits since it came into existence. This has been between 0.5% and 2% of the U.S. Supreme Court's overall caseload of merits cases in modern times. (These days the U.S. Supreme Court typically decides about 70 case a year on the merits and evaluates about 5,000 certiorari petitions each year.) Between 1789 and 1959, the Court issued written opinions in only 123 original cases. Since 1960, the Court has received fewer than 140 motions for leave to file original cases, nearly half of which were denied a hearing. The majority of cases filed have been in disputes between two or more states. The Court has generally accepted state party cases dealing with boundary and water disputes, but it has been much less likely to field original cases dealing with contract disputes and other subjects not deemed sufficiently substantial for the Court's resources. In practice, when a case in the U.S. Supreme Court's original jurisdiction is filed, it is almost always assigned immediately to a "special master" who develops the case until it is ready for U.S. Supreme Court review. The U.S. Supreme Court briefly allowed non-residents of a state to sue state governments in its original jurisdiction, but this authority was quickly eliminated by the passage of the 11th Amendment (which has also been interpreted as codifying the principal of a state's sovereign immunity from suits by its own citizens outside its own courts without its consent). In the Judiciary Act of 1789, Congress made the Supreme Court's original jurisdiction exclusive in suits between two or more states, between a state and a foreign government, and in suits against ambassadors and other public ministers. The Supreme Court's jurisdiction over the remainder of suits to which a state was a party was to be concurrent, presumably with state courts since the statute did not expressly confer these cases upon the inferior federal courts. Notably, this exclusivity rule does not apply to suits between a state and the United States, or to suits brought by states against non-residents (whether or not they are U.S. persons), although such suits have been interpreted to be within the original jurisdiction of the U.S. Supreme Court: In the 1892 case of United States v. Texas , Justice John Marshall Harlan ruled that since the federal judicial power extended to "cases in which the United States was a party," and the Court was granted jurisdiction over cases to which a state was a party, the Court would take jurisdiction in a United States suit against a state. Such suits by the United States increased after the 1890s and usually involved disputes with states over land, though in the late twentieth century they also included a few suits to enforce provisions of the Federal Voting Rights Act. As a result of the 11th Amendment and the 1789 Judiciary Act, the U.S. District Courts only have jurisdiction over states when they consent to suit in the forum (usually for federal law cases involving bankruptcies), or when the United States is a party and no private individuals are parties (as in the federal district court case Arizona v. United States mentioned in the comments) since U.S. District Courts have jurisdiction over all suits to which the United States is a party. U.S. District Court jurisdiction is limited, however, by doctrines of state sovereign immunity, to cases seeking only injunctive relief that seek to enforce the 14th Amendment to the United States Constitution (although this is circumvented, in part, by bringing suits against state officials as opposed to state governments themselves). So basically, states themselves can only be sued in U.S. District Courts by the United States for injunctive relief under the 14th Amendment. (For this purpose, unlike many other purposes under the U.S. Constitution, the term "state" does not include local governments which can be sued in federal court, and often are sued there for civil rights violations.) Also, despite the seemingly mandatory nature of the U.S. Supreme Court's original jurisdiction, it declines to hear about half of the cases presented to it in that capacity. The Supreme Court further limited its original docket by declaring that it would exercise discretion over whether to hear cases even if they were legitimately within the Court's jurisdiction. In a series of cases in 1971, including Ohio v. Wyandotte Chemicals Corp ., the Court declined to hear environmental pollution claims brought by states against corporations that dealt with complex and technical factual questions. The justices ruled that the states had other available forums to bring their claims and that the cases were not "appropriate" for the Court in light of its primary function as the nation's highest appellate tribunal. The Court resolved to examine the "seriousness and dignity" of claims so as to preserve its resources for consideration of appeals involving federal questions. The Supreme Court soon expanded its appropriateness doctrine to decline to hear some cases between two states, even where the Court's jurisdiction was exclusive. The U.S. Supreme Court also has the statutory authority (almost never used) under the All Writs Act (28 U.S.C. § 1651) to issue writs of habeas corpus filed directly in the U.S. Supreme Court rather than a lower court, although strictly speaking it doesn't add to the U.S. Supreme Court's jurisdiction. About 60 habeas corpus cases are filed directly in the U.S. Supreme Court in its original jurisdiction each year, although very few are granted. The text of the All Writs Act is as follows: (a) The Supreme Court and all courts established by Act of Congress may issue all writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principles of law. (b) An alternative writ or rule nisi may be issued by a justice or judge of a court which has jurisdiction. According to Wikipedia (with appropriate citation to authority): Application of the All Writs Act requires the fulfillment of four conditions: The absence of alternative remedies—the act is only applicable when other judicial tools are not available. An independent basis for jurisdiction—the act authorizes writs in aid of jurisdiction, but does not in itself create any federal subject-matter jurisdiction. Necessary or appropriate in aid of jurisdiction—the writ must be necessary or appropriate to the particular case. Usages and principles of law—the statute requires courts to issue writs "agreeable to the usages and principles of law".
Absent newly enacted law in response to the end of the separate sovereigns doctrine, the first case to which jeopardy attaches (generally speaking when a jury is sworn and the first item of evidence is presented to it) would bar subsequent prosecutions, without regard to whether it arose in state or federal court. It would be a race to the court house rule. This is how it works if there are multiple prosecutions within a state, for example, one commenced in a municipal court that is not part of a state court system, and another commenced in a state court of general jurisdiction.
Under Article VI of the US Constitution, the federal constitution and valid federal laws are the supreme law of the land, and judges in every state are bound to apply them regardless of anything in the laws or constitution of any state.* If a state legislature passes a law banning same-sex marriage, a state court is required under the federal constitution to instead apply the federal constitution (as interpreted by the US Supreme Court in Obergefell v. Hodges) and rule as though same-sex marriage is legal. When it comes to a federal court, things are even easier: a state cannot command a federal court to do anything. A federal court’s authority is laid out in Article III of the federal constitution and in federal statute, which (per Article VI) is supreme over anything in the laws or constitution of any state. There have been times where states attempted to challenge federal supremacy. Normally, this is handled by going to federal court. Decisions in state courts can ultimately be appealed to the US Supreme Court, which can reverse them if they incorrectly applied federal law. Most of the time, that’s the end of matters: when a federal court rules, state officials comply. Occasionally, that’s not enough. If a state disobeys the orders of a federal court, they can be enforced by federal agents. If even that isn’t enough, the President can deploy the armed forces to uphold federal authority. * There are situations which are more complicated, like when something is a federal crime but not a state crime. I can do more research on that if you want, but for now I’m going to leave it at “it’s more complicated.”
Short answer: Maybe. Long answer: The answer here varies from jurisdiction to jurisdiction. Normally, the process goes like this: The application for the warrant is usually made under seal or otherwise in secret to prevent the target from trying to hide evidence. So before it's been executed, you can pretty much forget about accessing it. After the warrant is executed, though, there are differing answers to this question. The Supreme Court gave us a test for this kind of question in Press-Enterprise II, which held that the First Amendment gives us a qualified right to access court proceedings and records. The right applies when public access makes sense using the "experience and logic" test: Has the Anglo-Saxon experience typically been to provide access, and does logic tell us that access has beneficial effects for the judicial process? But lower courts have disagreed about how to apply the test. The Eighth Circuit allowed access to warrants in a defense-industry corruption investigation in In re Search Warrant for Secretarial Area-Gunn, but the Ninth Circuit denied access in to warrants in the same investigation in Times Mirror Co. v. U.S. I think, though, that the Ninth Circuit decision would have come out differently if the investigation had already ended. Just to mix things up further, the Fourth Circuit has also allowed access, but based on common law principles of access, rather than the First Amendment. That was Baltimore Sun Co. v. Goetz. Same in the Second Circuit: In re Application of Newsday, Inc. Individual states also have their own rules, but those are of course subject to limits under the First Amendment. When I wanted a copy of a warrant, I would go first to the clerk of the court whose judge signed the warrant. I would tell them what I was looking for, and I pretty much always got it. I would rarely submit a FOIA request, especially if the warrant was issued by a federal agency. Those requests sit in a queue for months or years without being reviewed, and the agency virtually always denies the request anyway. When law enforcement agencies and courts have copies of the same record, you're almost always going to have better luck getting access from the courts, which are set to open by default. If the court denies the request, try again after there's an indictment, and again after the trial.
The UK Supreme Court (as you tagged in the question) uses an odd number for this exact reason. A recent case, Attorney General v Crosland [2021] UKSC 58, further explains: it is a very common feature of appeals in the UK generally that the appellate court consists of a larger panel than the court appealed from. It not infrequently happens that a party to an appeal to the Supreme Court wishes the court to depart from an earlier decision of the Supreme Court or of the House of Lords. In such a case the practice is for the appeal to be heard by an enlarged panel of seven or more justices, precisely to clothe it with that greater authority The statute establishing this Court provides: The Supreme Court is duly constituted in any proceedings only if all of the following conditions are met— (a) the Court consists of an uneven number of judges; (b) the Court consists of at least three judges; (c) more than half of those judges are permanent judges. (with the possibility of some deviation in special circumstances). This practice was previously followed in the House of Lords, before being made statutory when the Supreme Court was formed. The UK court does not sit en banc, partly because there are twelve permanent judges and that is an even number, and partly because the legal tradition hasn't held it to be worthwhile. An exceptional case was R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5, heard by eleven judges - a record! - which happened to be the entire Supreme Court at the time, since there was one vacancy. A panel of nine was used in Attorney General's Reference (No. 2 of 2001) [2003] UKHL 68, for the first time since R v Ball [1911] AC 47. Smaller numbers are more typical, such as five. For the Supreme Court of the United States, there are nine judges but they do not use panels. It is fairly common for some judges to recuse themselves because they had been involved with proceedings at a lower stage, or if there is a vacancy, and so there are cases where there are an even number of judges actually involved. The US court also has a practice of fairly complex patterns of concurring and dissenting opinions, with justices potentially joining more than one opinion, so it can be subtle to identify where the majority position really lies. It is therefore possible for there to be a tie. If there is a tie on appeal, then the lower court's decision stands, without precedential effect. For matters within the original jurisdiction of the Supreme Court, there is no consensus on what is meant to happen - see What happens if the US Supreme Court ties 4-4? for more.
If the Supreme Court is the final authority The Supreme court is not the final authority. The Supreme Court is the court of last resort, but that does not prevent its case law from possibly being superseded or invalidated by constitutional amendments or the enactment of legislation. Wouldn't past and future courts be of equal authority No. Whether in the form of statutes or court decisions, laws are supposed to preserve ordered liberty. That entails the need to keep up-to-date with the state or evolution of civilization. If the Supreme Court case law --aka authorities-- were deemed inexorably perpetual, the entire judicial system would become imminently useless due to its inability to respond to new challenges [in the civilization] which are (1) encompassed by prior SC authorities, and yet (2) not properly assessed therein.
There are a lot more differences than this, but if your teacher sums up what he/she means by that sentence. Here, specifically, in Civil Law, the decision of the courts must comply with the laws as enacted, which means there are specific statutes required to make something illegal. Common Law features Stare Decisis which basically means that if Case A is decided in one way, and Case B is a similar Case to Case B, Case B must yield the same decision for all cases in that jurisdiction and lower courts below that court. This means that while statutes (laws) can be made by a legislature, the courts can "make law" by deciding cases. For example, some States in the United States and England and Wales only recently (within the past 30 years) adopted an actual law that made murder illegal? Prior to that murder was illegal under Common Law Murder that had been based on precedence from bazillion cases before that said it's illegal. Nobody bothered to write it down in an actual law. There are several other big differences such as Inquisitorial vs. Adversarial nature of courts, how and when punishments are decided (The famous "Just following Orders" Defense was given in part because of this difference and a lack of understanding over it.), who is the trier of fact vs. who is the trier of law, but as far as what is "Law" this is a good single summation of the difference in a single sentence. But it really shouldn't be condensed to a single sentence.
Huge difference between a car and a house. For example, at least in Pennsylvania no warrant is required to search a vehicle on public roads. In other states there are so many easy pretexts that you practically have little protection from a full vehicle search (although the pretext will have to withstand strict scrutiny if evidence found in a search is used to charge you with a crime). Your house, on the other hand, still enjoys very strong fourth-amendment protections: One of my favorite U.S. Supreme Court cases on the subject is Florida v. Jardines, in which SCOTUS ruled that even approaching the front door with a drug-sniffing dog without a warrant constituted an illegal search. (The majority opinion is worth reading for its illumination of current law on this question.)