When inserting into a pg column of type bool, you cannot supply a PHP type of bool. You must instead use a string "t" or "f". PHP attempts to change boolean values supplied as parameters to strings, and then attempts to use a blank string for false.
Example of Failure:
pg_query_params('insert into table1 (bool_column) values ($1)', array(false));
Works:
pg_query_params('insert into lookup_permissions (system) values ($1)', array(false ? 't' : 'f'));