The right of habeas corpus is the constitutionally bestowed right of a person to present evidence before a court that he or she has been wrongly imprisoned.
The law just can't keep you locked up, execute you, or decide your fate without a determination of whether you've committed a crime or not.
Section 9 of the US constitution states - The Privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it.
Since September 11th, Habeas Corpus has been suspended and the government has the right to execute enemy combatants without trial. They've also passed law that they can execute American citizens without trial as well if they are considered a threat.
President Bush and Lincoln are the only two presidents to suspend Habeas Corpus and it is still currently suspended under the Obama administration (2010) giving the federal government full rights to assassinate whom ever they deem necessary without accusation or trial.