I believe the "Public Safety" exception to the requirement to read the Miranda warning is bordering on being unconstitutional.
The Fifth Amendment of the U.S. Constitution provides, "No person shall be held to answer for a capital, or 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."
The clauses incorporated within the Fifth Amendment outline basic constitutional limits on police procedure. The Framers derived the Grand Juries Clause and the Due Process Clause from the Magna Carta, dating back to 1215. Scholars consider the Fifth Amendment as capable of breaking down into the following five distinct constitutional rights: grand juries for capital crimes, a prohibition on double jeopardy, a prohibition against required self-incrimination, a guarantee that all criminal defendants will have a fair trial, and a promise that the government will not seize private property without paying market value. While the Fifth Amendment originally only applied to federal courts, the U.S. Supreme Court has interpreted the Fifth Amendment's provisions as now applying to the states through the Due Process Clause of the Fourteenth Amendment.
This Slate Magazine article describes the situation quite well. Please let me know what you think about this issue.