Who can get an expungement?

From the Website of the Allegheny County Criminal Division:

Prior to Act 134 of 2008, only non-convictions could be expunged, regardless of severity of the offense or the punishment. Non-convictions include verdict of not guilty; dismissal; withdrawal of charges, or nolle prosequi; Accelerated Rehabilitative Disposition; or Probation Without Verdict pursuant to the Controlled Substances Act.

The Accelerated Rehabilitative Disposition (ARD), Probation Without Verdict and Allegheny Service Institute (ASI) programs offer expungement as part of the plea bargain package. For ARD and Probation Without Verdict (PWV), an expungement for a first time offender is filed automatically by the Allegheny County Department of Adult Probation when all fines and costs have been paid and the defendant successfully completes all of the terms and conditions of the program. For ASI, the individual who completes the program must file a motion with the Department of Court Records, Criminal Division and pay the filing fee.  NOTE:  A Motion to Expunge was not filed automatically by the Department of Adult Probation for ARD participants prior to 1990.  Therefore, a defendant who completed ARD prior to 1990 must file a motion to expunge.

The passage of Act 134 now allows for the expungement of a conviction for a Summary offense provided the defendant has been free of arrest or prosecution for five (5) years following the conviction for that offense.