$(document).ready(function(){
    $('#targets').submit(function() {
        var error = 0;
        if (!($('#checkboxid').is(':checked'))) {
            error = 1
            alert("Please Tick the Agree to Terms of Use");
        }

        if (error) {
            return false;
        } else {
            return true;
        }

    });
});
        

I Agree to Terms of Use