Executive Branch Says Restricting Executive Branch's Power Unconstitutional

Brace yourselves because I'm about to dump a shocker of a news story on you. The executive branch has come out and said that it's unconstitutional to restrict its power:

The Obama administration had some harsh words Friday after a federal judge appointed by Obama said the government doesn't have a right to indefinitely detain anyone even remotely associated with terrorist groups.

[...]

Forrest's ruling oversteps the court's authority and infringes on Obama's power to act as Commander in Chief, according to the government's court filings.

Many constitutional scholars claim that the purpose of the Constitution is to restrict the state's power. Supposedly the document lists very specific powers granted to each branch of the state. Looking at the document I don't see where it states the president has the power to indefinitely detain an American citizen without due process. Are constitutional scholars incorrect in this assessment that the Constitution is meant to restrict governmental power or is the executive branch incorrect in claiming that it has the power to indefinitely detain individuals without due process? Thankfully the Constitution describes how these kinds of disputes can be resolved as it gives sole authority to decide such matters to a court of nine people that are part of the state. Wait... there seems to be some conflict of interest here.