Missouri constitution
Article I: bill of rights
Section 18(b)

Upon a hearing and finding by the
circuit court in any case wherein the accused is charged with a felony, that it is necessary
to take the deposition of any witness within the state, other than defendant and
spouse, in order to preserve the testimony, and on condition that the court make such
orders as will fully protect the rights of personal confrontation and cross-examination
of the witness by defendant, the state may take the deposition of such witness and
either party may use the same at the trial, as in civil cases, provided there has been substantial
compliance with such orders. The reasonable personal and traveling expenses
of defendant and his counsel shall be paid by the state or county as provided by law.