The Connecticut legislature passed a law saying that using emiment domain to seize private property for development by private companies qualified as 'public use' under certain circumstances. The Connecticut Supreme Court upheld that law. Why should the U.S. Supreme Court step into a state matter when the state constitution does not differ from the U.S. Constitution? Defining public usage is, and should be, a state matter.
So how , exactly , did the Supreme Court word it's decision, if I might ask?
Does this action stop at the Connecticut state line?
"Why should the U.S. Supreme Court step into a state matter when the state constitution does not differ from the U.S. Constitution?"
The Connecticut decision was definitive of the state constitution, but the SCOTUS has the last word on the US Constitution, including the Fifth Amendment, even if the state and federal constitutional provisions are identical.
"Defining public usage is, and should be, a state matter."
Not when the state law violates US Constitutional rights. For instance, had Connecticut interpreted its state laws and constitution to permit compelled confessions in violation of the US Fifth Amendment's self incrimination provision, I think you would see things differently.
A state does not have the prerogative of inventing Clintonesque definitions of words for the purpose of swindling citizens of their rights. The Supreme Court failed in its duty to reverse that abuse by the state of Connecticut.