Create Custom User Role for Tagging Custom Taxonomies

Hello!

I have recruited two of my blog’s readers to help me tag hundreds of prior posts using two custom taxonomies I’ve created, called ‘courts’ and ‘provisions’. Both readers are registered users with ‘subscriber’ privileges. I would like to give them privileges to tag posts with the custom taxonomy tags, but I would prefer not to give them full ‘editor’ privileges if possible.

I use WP 3.5.1 and the WooThemes Canvas theme (5.1.4). I am capable of inserting code into my functions.php file (that’s how I created the custom taxonomies) and of making some modifications to example code, but not of writing my own code from scratch, so if you have an example I could follow, that would be most appreciated. Thanks!