The statutes and the common law state not only the required qualifications to render men competent as jurors, but also state certain disqualifications which make them incompetent.

For the purpose of determining the qualifications of the jurymen from whom a jury is to be chosen, it is the universal rule for counsel of the respective parties to examine them under oath touching their competency as jurors.

The object of examining jurors upon their oaths is for the purpose of procuring a fair and impartial jury as guaranteed by the constitution, composed of twelve men of lawful age from the proper county or district, who are unprejudiced and unbiased, of fair character, possessing sound judgment, well informed and who understand the English language.

The statutes usually prescribe the order of examination.

In Illinois the jury shall be passed upon and accepted in panels of four by the parties, commencing with the prosecution and continuing thus until the twelve jurors shall have been selected.