Prevent tag submission

[Momiji]

I have a tag called "Tag Ex" and only specific groups are allowed to use this. I have created a before business rule so that an error appears when a user outside the groups tries to apply the tag with the same name. It will still allow outside users to submit the tag but when refreshing the record, the tag was not really saved. As what I have read (I'm not sure if this is true), Business Rule only fires after the user already tries to add the tag. So maybe that's why it still allows the user to submit the tag. What I want to happen is to really prevent submission.

Thanks!

[Naveen20]

If the flickering UX really bothers stakeholders, your only options would be hiding the tag entirely from unauthorized users (via ACL on the label table so they never see "Tag Ex" as an option) or customizing the tag widget itself, which gets upgrade-unfriendly fast. Hiding the tag via ACL so they can't even attempt it is the more practical route.