A writ or petition for habeas corpus in California is a defense motion to try to convince the courts that a person is being wrongfully imprisoned.
We get calls frequently from family members and loved ones asking if habeas corpus may be an avenue to getting someone released. It can be, but usually only in very limited circumstances.
There are two main considerations in evaluating the viability of a habeas corpus petition: timing and grounds.
In terms of timing, a habeas petition is only timely when all other remedies have been exhausted. Basically what this means is that the appeals process is over. If it is a recent conviction and there is still an opportunity to file an appeal, courts will want a prisoner to take the appeals route before taking the habeas route.
Second, there must be grounds for the motion ... usually a new issue that did not exist at the time of the appeal. This typically would be significant newly discovered evidence, or a change in the law that decriminalizes the conduct.
As you can see, the circumstances for a successful habeas petition in California are fairly narrow. But when the circumstances are right, it can be an effective way to serve justice by getting a wrongfully imprisoned person out of custody.