Technically, yes. California law permits electronic advance directives. But there are special rules associated with them. Just as with any advance directive, you must sign electronic versions. Further, your digital signature must comply with California’s digital signatures law or it must use technology approved by the National Institute of Standards and Technology.
If you are not fully confident that the system you are using complies with these standards, it is a better idea to sign a health care directive and living will on a hard copy. With FindLaw, you can create a health care directive and living will to print and sign in about an hour.