The DOJ, in an order issued by Undersecretary Regis Puno, said the investigating prosecutor did not commit any error that would justify reversal of the resolution against Cullen.
De Guzman filed the libel case against Cullen after the priest allegedly accused the mayor of coddling a death squad out to liquidate street children in this city.
The mayor was irked when Cullen sought help from non-government organizations and individuals from all over the world through the Internet, supposedly to pressure De Guzman to put a stop to such treatment of street children.
Several institutions did respond to Cullens call, further angering the mayor. De Guzman denied Cullens allegations which, he said, maligned him not only as a public official but also as a person.
Cullens lawyer earlier had filed a petition seeking a reversal of the city prosecutors resolution with the regional state prosecutors office. The petition was, in turn, elevated to the DOJ.
De Guzman said there was no basis for Cullens accusations, noting that Davao City was named the countrys "Most Child-Friendly City" for the second straight year by the United Nations International Childrens Fund (Unicef).
Cullen, who heads an Olon-gapo-based NGO involved in a campaign against child abuse, is out on temporary liberty after posting a P10,000 bail bond. Edith Regalado