"No person shall be held to answer for a capital, otherwise infamous crime, unless on a presentment or indictment of a grand jury, except in cases arising in the land or naval forces, or in the militia, when in actual service in time of war or public danger; nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation." That is the Fifth Amendment of the United States Constitution, and it's one of the most important ones because it protects your legal rights from the government. Specifically, it states that you can't be punished for a crime without a trial by jury, unless in a case involving the military during a time of war. Furthermore, it states that no one can be punished or brought to trial more than once for the same crime, and is not required to provide testimony of any kind against himself. Finally, the Fifth Amendment states that no one can be deprived of his life, freedom, or property without a fair trial, and that the government cannot take private property from a citizen unless a fair compensation is present.
Personally, I think this is one of the greatest amendments to our Constitution in existence. It's absolutely necessary to have a safeguard from the government just locking people up and taking their property. After all, politicians aren't the angels they wish we'd think they are. Countries like Russia struggle without laws like our Fifth Amendment, and ultimately, without basic freedoms like that, a country will fall.
An event of controversy involving the Fifth Amendment involves the Supreme Court Case of Dred Scott vs. Sandford. Although the Supreme Court decided that African Americans, free or not, weren't citizens and therefore couldn't sue in public court, as well as stating the federal government couldn't regulate slavery in territories acquired after the creation of the United States, it was one of the first clear examples of due process of law.