The wp_terms_checklist_args filter allows you to modify the arguments array in wp_terms_checklist, which is located in wp-admin/includes/template.php. wp_terms_checklist is the taxonomy-independent version of wp_category_checklist and only works with hierarchical taxonomies.

It accepts two arguments:

1. array $args The arguments array (see wp_terms_checklist for the defaults
2. int $post_id The post id

Example:

Let’s say you have a hierarchical taxonomy called ‘Media Categories’ — with a slug of media_cats — that you’re using with media attachments. And let’s say you don’t want the selected categories to float to the top of the box (the default behavior).

	<?php
	/**
	* Disable 'checked_ontop' for Media Categories taxonomy
	*
	* @see wp_terms_checklist()
	*
	* @param array $args An array of arguments.
	* @param int $post_id The post id.
	*
	* @return array The arguments array.
	*/
	function wpdocs_no_top_float( $args, $post_id ) {
	// If the taxonomy is set and equals 'media_cats'
	if ( isset( $args['taxonomy'] ) && 'media_cats' == $args['taxonomy'] )
	$args['checked_ontop'] = false;
	return $args;
	}
	add_filter( 'wp_terms_checklist_args', 'wpdocs_no_top_float', 10, 2 );

view raw wp_terms_checklist_args.php hosted with by GitHub

View the code example on Gist.