The party brought before the court on the return of the writ may deny or controvert any of the material facts or matters set forth in the return, or except to the sufficiency thereof, or allege any fact to show either that the imprisonment or detention is unlawful or that the party is entitled to be discharged. The court thereupon must proceed in a summary way to hear such proof as    may be produced against such imprisonment or detention, or in favor of the same, and to dispose of such party as the justice of the case may require, and has full power and authority to require and compel the attendance of witnesses, by process of subpoena and attachment, and to do and perform all other acts and things necessary to a full and fair hearing and determination of the case. The court may allow the return to be amended according to the facts of the case, whenever it may be deemed necessary.