Parole is a conditional release from prison. If you violate the conditions of the release, the gatekeeper who determines whether you are going to be re-incarcerated is the Parole Board. The trick to not being re-incarcerated is to convince the Parole Board you are not a risk or danger to society.
All inmates released on parole are given a list of conditions they are not supposed to violate. The conditions vary slightly from State to State, but typically include restrictions on:
Most conditions are relatively easy to satisfy, although they are restrictions and can impact the parolee's ability to control their own life. Society sees these restrictions as a safeguard to help keep society safe from the parolee, who they do not trust to stay on the 'straight and narrow' path. Violating these typical conditions is called a technical violation. Depending on the State, the type of condition that was violated, and the number of times it (or, they if more then one condition was violated) the Parole Board will determine whether to violate your parole and send you back to prison.
Even an arrest for a new crime, felony, offense, misdemeanor, violation or motor vehicle matter is considered a technical violation, unless the arrest becomes a conviction by either plea or verdict after trial. Depending on the State and the type of conviction, these parole violations are the most serious and are most likely to result in you being re-incarcerated.
Typically, a failed drug screen is also viewed as a more serious violation, as the mere possession of the drugs you are being screened for is a crime. Your positive drug test simply establishes the proof that you committed a crime. Certain actions you may have taken while under the influence of the drugs, could also be the basis to charge you with additional offenses, such as driving under the influence (DUI).
As with all things in life, you have choices in how to present the situation to the Parole Board.
If you failed to report, get the proof that the transportation was not available. If you were working and the only way to avoid the loss of the job was to miss the report date, then get proof that you were working. If you have an addiction problem, start attending NA/AA meetings on a regular basis, and ask the parole officer for treatment assistance. At least then when you do test positive for the drugs, you can establish an argument that you were at least trying to comply with the condition.
Each type of condition has similar types of defensive arguments that can be constructed, limited only by your circumstances, your resourcefulness and the relationship you have with your parole officer.