Is there a way to make report filters mandatory
If you are setting the filter value (with a default) and don't want the user to change it, you can use the 'no_display' parameter to hide the filter from the user.  (Per the docs here: https://wiki.civicrm.org/confluence/display/CRMDOC/CiviReport+Reference#CiviReportReference-filters ) Unfortunately, it doesn't look like the Required parameter is an option for filters like it is for fields.