Lil Za may have just benefited in a BIG way from Justin Bieber's legal woes ... because we've learned his felony vandalism charge for breaking a jail phone will be REDUCED to a misdemeanor.
Za was busted during the search of Bieber's home in January after cops found MDMA (Ecstasy) and Oxycodone. He was taken to jail where he flew into a rage and broke the jail phone. For that, he was charged with FELONY vandalism.
Law enforcement sources tell TMZ ... the L.A. County D.A. has agreed to reduce the charge to a misdemeanor because they say the phone was not even worth $400 -- and under the law ... vandalizing property worth less than $400 is a misdemeanor.
As for Za's drug charge ... we're told the likely disposition will be a drug diversion program, where Za would plead guilty to felony drug possession, but after completing a drug ed course and keeping his nose clean for a year ... the charge would be erased from his record.