instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
What would an engine driver have to do to adjust the more modern type of valve?, Context: Steam engines frequently possess two independent mechanisms for ensuring that the pressure in the boiler does not go too high; one may be adjusted by the user, the second is typically designed as an ultimate fail-safe. Such safety valves traditionally used a simple lever to restrain a plug valve in the top of a boiler. One end of the lever carried a weight or spring that restrained the valve against steam pressure. Early valves could be adjusted by engine drivers, leading to many accidents when a driver fastened the valve down to allow greater steam pressure and more power from the engine. The more recent type of safety valve uses an adjustable spring-loaded valve, which is locked such that operators may not tamper with its adjustment unless a seal illegally is broken. This arrangement is considerably safer.[citation needed]
answer:
seal illegally is broken


question:
What is a legal doctrine that obligates courts to follow historical cases when making a ruling on a similar case, Context: Federal law originates with the Constitution, which gives Congress the power to enact statutes for certain limited purposes like regulating interstate commerce. The United States Code is the official compilation and codification of the general and permanent federal statutes. Many statutes give executive branch agencies the power to create regulations, which are published in the Federal Register and codified into the Code of Federal Regulations. Regulations generally also carry the force of law under the Chevron doctrine. Many lawsuits turn on the meaning of a federal statute or regulation, and judicial interpretations of such meaning carry legal force under the principle of stare decisis.
answer:
stare decisis


question:
Which mitigating factor are we concerned with in the passage?, Context: The United States Supreme Court in Penry v. Lynaugh and the United States Court of Appeals for the Fifth Circuit in Bigby v. Dretke have been clear in their decisions that jury instructions in death penalty cases that do not ask about mitigating factors regarding the defendant's mental health violate the defendant's Eighth Amendment rights, saying that the jury is to be instructed to consider mitigating factors when answering unrelated questions. This ruling suggests that specific explanations to the jury are necessary to weigh mitigating factors.
answer:

mental health