Make taxonomy mandatory field

I have created a custom taxonomy in CustomPress and want to make it mandatory when user is creating or editing a listing.

Here is the code that controls the Taxonomies for my edit listing page / page-update-listing.php
If you would like me to upload the full page code please just let me know.

<!-- Start Taxonimy, Category and custom All Services-->
		//get related hierarchical taxonomies
		$taxonomies = get_object_taxonomies('directory_listing', 'objects');
		$taxonomies = empty($taxonomies) ? array() : $taxonomies;

		//Loop through the taxonomies that apply
		foreach($taxonomies as $taxonomy):
		if( ! $taxonomy->hierarchical) continue;
		$tax_name = $taxonomy->name;
		$labels = $taxonomy->labels;
		//Get this Taxonomies terms
		$selected_cats = array_values( wp_get_post_terms($listing_data['ID'], $tax_name, array('fields' => 'ids') ) );


		<div id="taxonomy-<?php echo $tax_name; ?>" class="dr_taxonomydiv">
			<label><?php echo $labels->all_items; ?></label>

			<div id="<?php echo $tax_name; ?>_all" class="dr_tax_panel">
				$name = ( $tax_name == 'category' ) ? 'post_category' : 'tax_input[' . $tax_name . ']';
				echo "<input type='hidden' name='{$name}[]' value='0' />"; 		// Allows for an empty term set to be sent. 0 is an invalid Term ID and will be ignored by empty() checks.
				<ul id="<?php echo $tax_name; ?>_checklist" class="list:<?php echo $labels->name; ?> categorychecklist form-no-clear">
					<?php wp_terms_checklist( 0, array( 'taxonomy' => $tax_name, 'selected_cats' => $selected_cats, 'checked_ontop' => false ) ) ?>
		<?php endforeach; ?>
<!-- End Taxonimy, Category and custom All Services-->

This is a multi-site and I was unable to find where to activate support access. If you need me to send login creds let me know.