It depends on the reason for the failure. The results of the polygraph are unreliable and inadmissable at an evidentiary hearing. However, what you say during a polygraph examination may be considered admissions, making your statements perfectly admissable as evidence of a probation violation. So, what the machine says is inadmissable, but what you say is probably admissable to revoke your grant of probation.
Law Office of Andrew Limberg, APLC 380 S. Melrose Dr., #329 Vista, CA 92081 (760) 806-4381
Get another lawyer. Anyone who says probation can not use a polygraph against you needs to do another year at San Diego State.
The results, themselves, may not be admissible against you. However, any statements and/or admissions you make during the polygraph will.
Law Offices of David Shapiro 3555 4th Avenue San Diego, CA 92103 (619) 295-3555
I had a case several years back where my client in a Riverside County case sought a transfer of his probation supervision to San Bernardino County and after several years of successful probation, his PO tried to force him, a misdemeanant sex registrant, to take a polygraph. I objected in writing and quickly added it to calendar because such a test was never ordered as a term of probation. The court agreed with me and we were able to block the poly in that and any other county.