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Authority's authorizer methods let you check anything you like in order to decide what a user can do.
resource.looks_spammy? && user.points > 200 || is_spam_cleanup_day?(Date.today)
However, one of the most common use cases is checking user roles. The rolify gem is a nice fit for this, making it easy to create and assign roles and query based on them.
So our example above might be amended as:
user.has_role?(:admin) || resource.looks_spammy? && user.points > 200 || is_spam_cleanup_day?(Date.today)
See the great documentation and wiki for rolify for setup and usage details.