The Fifth Amendment does several different things which have different purposes. It’s important to understand each of them.
Let’s do them in order.
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[li]Grand jury indictment[/li]
The Fifth Amendment guarantees that the federal government can not prosecute a felony (“capital or otherwise infamous crime”) without an indictment by a grand jury. The grand jury was invented in England and has its roots in magna carta (and even before then) as a way to prevent abuses by monarchs and feudal lords. The point of the grand jury is that a person should not have to go to the expense and trouble of mounting a legal defense to a crime unless the sovereign can convince the accused’s peers that their is sufficient evidence to make a trial necessary.
Most jurisdictions (including a majority of US states) have replaced grand juries with pretrial evidentiary hearings before a judge, but they remain in the federal system.
[li]Double jeopardy[/li]
The Fifth Amendment guarantees that the same person will not be charged twice for the same crime in the same jurisdiction (“to be twice put in jeopardy of life or limb.”) The purpose here is to prevent an abusive prosecutor from harassing a person by repeatedly charging them with the same crime, even if the defendant is found not guilty each time. An acquittal is an absolute bar to retrial on the same charges (in the same jurisdiction), even if new evidence is discovered later, on the theory that society is best served by strong protections against an abusive state at the cost of criminal justice being imperfect. The fifth amendment does not preclude charges from multiple jurisdiction relating to the same set of criminal acts (e.g. a suspect may face both federal and state charges related to the same crime.)
[li]Protection from self-incrimination[/li]
The Fifth Amendment guarantees that a person can not be forced to answer questions against his will, where such an answer might reveal incriminating information, or be viewed as incriminating. (“Taking the fifth.”) It also means that in a criminal case, the prosecutor can not call the defendant as a witness (“compelled in any criminal case to be a witness against himself.”) This also has its roots in English law, based on the theory that the government must prove guilt, and that the defendant need not prove his innocence. This protection is rooted in abuses such as the torture or badgering of criminal defendants.
[li]Due process[/li]
The Fifth Amendment guarantees that people can not be punished (“be deprived of life, liberty, or property”) without “due process,” where “due process” is defined by a long history of statutes and case law. Basically, in the context of criminal justice, it means that evidentiary and trial procedures must be clearly defined, and the government must follow them, instead of acting arbitrarily. That’s a good thing.
[li]Just compensation[/li]
Related to the above, the Fifth Amendment guarantees that if and when the government takes private property, (eminent domain), they must provide compensation to the owner and the compensation must be “just,” meaning, a fair market value for the property.
[/ol]
With regard to the Fifth Amendment, probably what people most often refer to, are the second and third items: double jeopardy and self-incrimination. I think those are quite reasonable protections to have in place in any criminal justice system.