One of my favorite quotes and I don't know who to attribute it to and I'm also paraphrasing it goes something like this: "If the law is so straightforward, why is it that five Supreme Court Justices have to teach the other four Supreme Court Justices the law every year." Not only is that true, what is also true, is that Supreme Court Justices will overturn cases with similar circumstances at different times, or simply make new law which is not in keeping with previous precedents. This makes it rather problematic for us to blindly follow the law.
For instance of the former, in which the basic legal principle is "stare decisis" which roughly translates into "the decision remains", we will take the case of Plessy v. Ferguson of 1896 in which the Supreme Court overwhelmingly ruled (7-1) that the Louisiana state provision that mandatedracial segregation in public facilities was in fact, constitutional. This was overturnedby an unanimous Supreme Court in 1954 in Brown v. the Board of Education in which it was declared that "separate educational facilities are inherently unequal" because they violated the 14th Amendment Equal Protection Clause. Yet, the 14th Amendment was ratified in 1868 and Justice Brown writing for the majority in the Plessy v. Ferguson decision specifically stated that " The object of the amendment [14th] was undoubtedly to enforce the absolute equality of the two races before the law, but, in the nature of things, it could not have been intended to abolish distinctions based upon color…" While, the Justice Brown majority decision of 1896 reeks of absolute hypocrisy, that was the law of the land until 1954 and those that tried to violate the "separate but equal" clause that Justice Brown affirmed, paid the price with jail time, beatings, discrimination, and a lesser status in their own country.
For an example of the Supreme Court making new law, we need not look further than the infamous Miranda v. Arizona of 1966. It is upon this case, the 'Miranda warning,' was created. Chief Justice Warren wrote: "In order fully to apprise a person interrogated of the extent of his rights under this system, then, it is necessary to warn him not only that he has the right to consult with an attorney, but also that, if he is indigent, a lawyer will be appointed to represent him... Once warnings have been given, the subsequent procedure is clear. If the individual indicates in any manner, at any time prior to or during questioning, that he wishes to remain silent, the interrogation must cease." This later was summarized and became known as the Miranda warning which is familiar to anyone that has watched a Law & Order television program or has been arrested in the real world. In the dissent of this 5-4 majority decision, Justice Harlan wrote: "To incorporate this notion into the Constitution requires a strained reading of history and precedent and a disregard of the very pragmatic concerns that alone may on occasion justify such strains." The upshot being that prior to this Court's decision of 1966, the police were free to receive and act upon non-coerced confessions but after this decision, the police were mandated to provide appropriate warnings of both counsel and silence or that evidence was subject to being dismissed.
The law is not always right, even the Supreme Court gets it wrong from time-to-time, that's why every year five Supreme Court Justices have to teach the other four Supreme Court Justices the law.