Declaring a diplomat persona non grata is only one of various remedies available to a host nation, and usually the most drastic. A recent example is the declaration by the Philippine Department of Foreign Affairs reported May 13, 2012 in Panama embassy employee accused of raping Filipina--He has been declared persona non grata.
The Gulfnews.com article relates also the bilateral responses. In this instance, the declaration followed the departure of the diplomat from the host nation after the accusation of a crime. The correspondent, Gilbert P. Felongco, notes:
The incident also led Senator Vicente Sotto III to ask the government to establish clear guidelines involving foreigners who use diplomatic immunity as a shelter whenever they commit a crime overseas.Clear rules are usually useful to avoid bias and ensure transparency and predictability. On the other hand, pragmatic and political considerations do not always lend themselves to the clear rule-bound implementation of remedies available against diplomatic and consular persons. -- Clemens Kochinke, partner, Berliner, Corcoran & Rowe, LLP, Washington, DC.