Quote Originally Posted by lat9 View Post
Thanks for the clarification! You can use the following code in that auto-loaded observer:
Code:
            case 'NOTIFY_USPS_UPDATE_OR_DISALLOW_TYPE':
                // -----
                // Disallow "Ground Advantage" if there are no products with a tax_class_id of 4
                // in the cart.
                //
                if (stripos($p1, 'USPS Ground Advantage') !== false) {
                    if ($_SESSION['cart']->in_cart_check('products_tax_class_id', '4') == 0) {
                        $p2 = false;
                    }
                }
                break;
Worked like a charm--thank you!