 Some courts and observers opine that cases "must" be dismissed because this is a constitutional bar, and there is no "case or controversy"; others have rejected the pure constitutional approach and adopted a so-called "prudential" view, where dismissal "may" depend upon a host of factors, whether the particular person has lost a viable interest in the case, or whether the issue itself survives outside the interests of the particular person, whether the circumstance are likely to recur, etc.In actual practice, the U.S. federal courts have been uneven in their decisions, which has led to the accusation that determinations are "ad hoc" and 'result-oriented.