At JW's request, converted the Court field in the main Trial table from a single item to a one-to-many. Here's the SQL:

/*Create the new linking table.*/

CREATE TABLE IF NOT EXISTS `courts_to_trials` (
  `ctt_ctt_id` int(11) NOT NULL auto_increment,
  `ctt_tr_id_fk` int(11) default NULL,
  `ctt_ct_id_fk` int(11) default NULL,
  PRIMARY KEY  (`ctt_ctt_id`),
  KEY `ctt_ibfk_1` (`ctt_tr_id_fk`),
  KEY `ctt_ibfk_2` (`ctt_ct_id_fk`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ;

/*Add constraints to the new linking table.*/

ALTER TABLE `courts_to_trials`
  ADD CONSTRAINT `ctt_ibfk_1` FOREIGN KEY (`ctt_tr_id_fk`) REFERENCES `trial` (`tr_id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `ctt_ibfk_2` FOREIGN KEY (`ctt_ct_id_fk`) REFERENCES `court` (`ct_id`) ON DELETE CASCADE ON UPDATE CASCADE;
  
/*Copy existing data.*/

INSERT INTO `courts_to_trials` (`ctt_tr_id_fk`, `ctt_ct_id_fk`) (SELECT `tr_id`, `tr_court` FROM `trial`);

/*Delete original field.*/

ALTER TABLE `trial` DROP FOREIGN KEY `tr_ibfk_1`;
ALTER TABLE `trial` DROP COLUMN `tr_court`;

Updated the local_classes.php file appropriately. Tested on dev, then ran on live. In the process of testing, found a little bug: when deleting a record, the table that comes back still has all the old column-header filter fields in it. I'll fix that now.