Palin has announced that her staff won't comply with subpoenas:
Yes indeed, friends, dramatic proof that Sarah Palin will be Ready On Day One. It took months for Dick Cheney to start ignoring subpoenas.
The legislature, of course, has the full right to investigate the executive branch. That's part of the checks and balances that are the foundation of American democracy. Ignoring a subpoena is denying the basis of the rule of law; all by itself it is grounds for impeachment.