What is the test for equitable tolling in a habeas case?

As we have reiterated on numerous occasions, the purpose of equitable tolling is to "prevent the unjust technical forfeiture of causes of action." Jones v. Blanas , 393 F.3d 918, 928 (9th Cir. 2004) (quoting Lantzy v. Centex Homes , 31 Cal.4th 363, 2 Cal.Rptr.3d 655, 73 P.3d 517, 523 (2003) ). That is, equitable tolling entitles a prisoner who experiences an unexpected hardship to additional time when he would otherwise be denied his day in court. In applying these equitable considerations, we must bear in mind that prisoners are generally pro se and are not only without the resources to hire counsel but also most often without the knowledge or ability to prepare timely and adequate habeas petitions by themselves. Allowing courts to forfeit a petitioner's right to equitable tolling because in the court's judgment the prisoner could have filed earlier in the statute-of-limitations period had he scheduled his legal work differently would undermine the equitable principles that underlie the use of equitable tolling in habeas cases.