Access restriction using tags

Hi,
I have certain tags with an access restriction to certain roles.
When I have only one tag for a given post, no problem.
If I have a list of tags, the program looks at the first tag. If that tag is allowed for the role of the user, he can access the post, regardless of the other tags ( if the first tag as no restriction at all, the program looks at the next tag ).
Would it be possible to make the program look at all the tags of the list and allow access only if all the tags permit ?
Thank you for your pluging, it is great.