The First Circuit has determined that the "stop-time" rule, which dictates than an applicant for suspension of deportation or cancellation of removal ceases to accrue continuous physical presence in the United States on the date that a charging document is served on him, applies retroactively to Orders to Show Cause issued prior to the effective date of the stop-time rule (April 1, 1997).
The full text of Santos-Quiroa v. Lynch can be found here: http://media.ca1.uscourts.gov/pdf.opinions/15-1685P-01A.pdf