Why is a reviewer 'locked' from being a reviewer for a journal submission?

The OJS system will respect the review workflow that has been set for the journal. If the journal has opted to use a workflow where the author should be anonymous to the reviewer then it will prevent the assignment of reviewers who have other user permissions that would allow them to see the author details.

In most cases, this is likely to be a user with both Reviewer and Journal Editor permissions. As an Editor can see all submission data, assigning them as a reviewer will mean that they would be able to break the policy of author anonymity.

When a user has such conflicting permissions, the below message will be displayed within the review assignment options:

This reviewer is locked because they have been assigned a role which allows them to view the author's identity. Anonymous peer review can not be guaranteed. Would you like to unlock this reviewer anyway? Unlock

If the handling editor wishes to assign this user as a reviewer then they can override the restriction by clicking the ‘unlock’ link at the end of the sentence*.

The handling editor will then be able to assign them as a reviewer in the normal method.

*it is not recommended that this is done unless in exceptional/agreed circumstances as the public peer review policy should remain intact.