Excerpt from the Virginia Code:
§ 19.2-262. Waiver of jury trial; numbers of jurors in criminal cases; how jurors selected from panel.
A. In any criminal case in which trial by jury is dispensed with as provided by law, the whole matter of law and fact shall be heard and judgment given by the court. In appeals from juvenile and domestic relations district courts, the infant, through his guardian ad litem or counsel, may waive a jury.
B. Twelve persons from a panel of not less than 20 shall constitute a jury in a felony case. Seven persons from a panel of not less than 13 shall constitute a jury in a misdemeanor case.
C. The parties or their counsel, beginning with the attorney for the Commonwealth, shall alternately strike off one name from the panel until the number remaining shall be reduced to the number required for a jury.
D. In any case in which persons indicted for felony are tried jointly, if counsel or the accused are unable to agree on the full number to be stricken, or, if for any other reason counsel or the accused fail or refuse to strike off the full number of jurors allowed such party, the clerk shall place in a box ballots bearing the names of the jurors whose names have not been stricken and shall cause to be drawn from the box such number of ballots as may be necessary to complete the number of strikes allowed the party or parties failing or refusing to strike. Thereafter, if the opposing side is entitled to further strikes, they shall be made in the usual manner.