Answer to Question 1
There are a dizzying number of court cases that attempt to balance the line between private rights and public safety. The Fourth Amendment governs stops and frisks, along with searches and seizures. The Fifth Amendment and the Miranda case address custodial police interrogations. The legal rules regarding reasonable suspicion, probable cause, and custodial interrogation are often based on a totality of circumstances in each specific case. Thus, not all possible factual scenarios have been addressed by the courts. In fact, they never will be. Ethics becomes a useful guide because laws can never anticipate the innumerable variations in circumstances that police will face. Court decisions are of little value to police in making current decisions or to the public who are the subjects of police action. Ethics offers an objective standard by which officers may go a step further in following the law. It provides clear guidance, in advance, in cases where the law's application is still unclear, undecided, or unknown.
Answer to Question 2
High-court judges at the federal level are employed for life and don't need to fear losing their jobs for issuing unfavorable decisions. Higher courts exert direct control over lower courts through their judicial authority and rule-setting. Lower courts are expected to follow precedents.
Lower courts do not have the luxury of lifetime positions and their decisions can influence their ability to maintain their position. Therefore, lower courts may sometimes not want to follow the higher court rulings. Lower courts can ignore the higher court's decisions or implement the decisions sparingly as a means to shape the controls of the higher courts.