The trial of country singers Tim McGraw and Kenny Chesney was postponed Thursday because the presiding judge had to be taken to the hospital and placed in critical condition after complaining about breathing problems. McGraw, 34, and Chesney, 33, were arrested June 3 after performing at the George Strait Music Festival in Buffalo, N.Y. McGraw allegedly attempted to pull a police sheriff off of Chesney, who was riding a police horse. Chesney allegedly had permission to ride the horse from the owner's daughter and refused to dismount when ordered by the Erie County sheriff. McGraw faces charges of assault, resisting arrest and a harassment violation. If the judge can't return, the trial will be declared a mistrial and proceedings will start all over again, prosecutors told The Associated Press. McGraw is married to country superstar Faith Hill, who has been a regular spectator at the trial.