An excerpt from "Blue Letter Bible.org" entitled, "Don Stewart :: In What Sense Will Believers Judge Angels?" states: "The judgment of angels is something that has been given to believers. Though humanity has been made a little lower than the angels in nature, those who have trusted the Lord will be given the responsibility of judging them in the age to come.
Nature of Judging
The nature of the judgment of the angels is not stated, but judgment does not imply condemnation. Since the good angels do not sin, there is nothing for which to condemn them. The judgment of angels most likely has to do with rulership in the kingdom. The Bible teaches that believers will be rulers over different aspects of the kingdom of God. Jesus made this clear in one of His parables." This article may be viewed at: Don Stewart :: In What Sense Will Believers Judge Angels?/blueletterbible.org
Reference: 1 Corinthians 6:3