In March of 2010 the United States Supreme Court ruled that in any criminal case, the defense attorney is required to tell the client he could be deported if he pleads guilty. The case was Padilla v. Kentucky and it held criminal defense attorneys have a Sixth Amendment obligation to tell clients the implications of pleading guilty in any case.
This week the United States Supreme Court clarified this ruling and held that it only applies to cases which were decided AFTER March 2010, when Padilla was decided. Unfortunately, cases where a defendant was not warned of these implications by his defense attorney before March 2010 have no recourse if they are currently facing deportation charges as a result of a guilty plea. The court found this requirement was not retroactive because it was a new rule established by the court.