In what circumstances will a court consider whether there is manifest necessity to declare a mistrial on the grounds that evidence has been improperly seized?

In State v. Thompson, 148 W.Va. 263, 134 S.E.2d 730, cited in support of the reversal of the Van Houten conviction, a question on appeal was [61 Cal.App.3d 227] whether there was 'manifest necessity' for declaring a mistrial on the ground that certain evidence (unlawfully seized) had been received erroneously. On appeal therein, it was held that the erroneous ruling did not constitute 'manifest necessity' for declaring a mistrial. After making that decision, the reviewing court proceeded, by way of dictum, to state examples of 'manifest necessity,' and in so doing included an occurrence such as illness or death of counsel, which was not involved in that case. In the present case, however, the footnote above referred to seems to be contra to the dictum in the cited West Virginia case. The footnote states, in part, that each case will have to be decided on its own facts; and that no per se rule can be stated.