According to this article from GMA News: http://www.gmanews.tv/story/211475/new-findings-of-plagiarism-by-sc-justice
On October 12, 2010, the SC cleared Del Castillo of plagiarism saying he acted in good faith and blamed instead the Microsoft Word program. “As it happened, the Microsoft word program does not have a function that raises an alarm when original materials are cut up or pruned," the Supreme Court said.
What next?! Blame a food processor manufacturer for cutting off your fingers because blenders don't have a feature that warns you when you put your hand in it while it's on? How about knives that don't have a warning feature when it's about to cut someone?
Seriously though, by it's nature, a word processor is supposed to edit documents. Do you honestly expect MS Word to add a feature to warn you that it is doing it's job?