Parental gatekeeping is a necessary strategy to protect children from parents suffering from alcohol or drug above or committing violent or neglectful acts. In those scenarios, the other parents have the right to restrict contact.
Another more sinister definition of parental gatekeeping involves one parent with primary physical custody and the other enjoying a visitation schedule. One disagreement arises, which is normal in any post-divorce relationship. However, the custodial parent reacts by forbidding scheduled visitation or requests a new parenting plan to provide them with more time.