There are at least two projects with the name "Murphy's Law":

1) Murphy's Law are a New York Hardcore (NYHC) band. The band’s line-up has constantly changed, with the exception of lead singer Jimmy Gestapo, who has remained throughout.

Now in 2013 its the reuniting of Todd Youth with Jimmy Gestapo
Murphy's law again remains one of the original and legends of the NYHC scene.

2) Murphys LaW is a Norwegian pop-rock band best known for competing in MGPjr 2010 and reaching the contest’s finals round. The members include vocalist Mads Sølsnes Gjetmundsen, guitarist Iver Armand Tandsether, drummer Jostein Braaten, and bassist Andreas Rukan.