This book analyses the legal situation of prisoners who are deprived of their liberty beyond the period stipulated in the criminal sentence. The right to liberty must prevail, since this guarantee should be deprived when there is a violation of a legally imposed penal rule. The sentence, which can be carried out through imprisonment, is stipulated in a conviction. From this point of view, overstaying the sentence in prison can be considered illegal imprisonment. This means that extrapolated imprisonment is included in the list of unlawful imprisonment, considering that the convict's stay in prison can cause irreparable damage, and the state must observe and compensate for this omission in the application of the sentence imposed.