Where is this granted?

Can someone explain to me where the constitution enumerates these dictatorial powers to the executive? Huh? It doesn't? Maybe someone ought to tell this administration.

WASHINGTON — In the growing battle between the White House and Congress, the administration will block the Justice Department from prosecuting any contempt charges that Congress may bring as a result of the administration's claim of executive privilege, according to a news report.

Administration officials have discussed the plan for several weeks, a move that could derail ongoing attempts in Congress to uncover new documents or testimony in the investigation of last year's firings of several U.S. attorneys, The Washington Post reported.

"A U.S. attorney would not be permitted to bring contempt charges or convene a grand jury in an executive privilege case," an unnamed administration official told The Washington Post, adding, "A U.S. attorney wouldn't be permitted to argue against the reasoned legal opinion that the Justice Department provided. No one should expect that to happen."

Here's the full report.