Pleading and Proving Prior Convictions and Prison Terms.
Having a prior felony conviction that you were sentenced to prison on may enhance any future felony sentence. Depending on its nature, a prior felony conviction may be used to enhance a sentence imposed under the determinate sentencing law. Penal Code section 667.5(b) provides fora 1-year sentence enhancement for each prior prior separate prison term served county jail term imposed under Penal Code section 1170(h) for any felony. There is a "washout" period after which the prior may not be used. Under California law priors have a 5-year washout period, which means that the defendant must have been free from both prison custody or imposition of a county jail term under Penal Code 1170(h) and the commission of an offense resulting in a felony conviction for that period.
Essentially, what this means is that if you are convicted of a felony offense and are not granted probation and have to serve an actual term then any future felony conviction within 5 years from your last term of custody will result in an additional 1 year. The court has the discretion to not sentence you to the additional 1 year in custody if facts and circumstances would justify.
If you are facing a new felony charge and have a prior felony enhancement alleged it is good idea to contact an attorney immediately. Often times I have experienced enhancements incorrectly charged which if not had been thoroughly investigated would have resulted in a client receiving unnecessarily an additional year of custody.