gistfile1.txt

<?php

/**
 * Implement of drush_hook_COMMAND_validate().
 *
 * Prevent overwriting your prod db.
 * Put this in your ~/.drush folder
 */

function drush_policy_sql_sync_validate($source = NULL, $destination = NULL) {
  if ($destination == '@prod') {
    return drush_set_error(dt('Per examples/policy.drush.inc, you may never overwrite the production database.'));
  }
}