Family members of elderly victims of undue influence - a phenomenon often connected with elder financial abuse - recoil in disbelief when learning of an elder's coerced gift or bequest property transfers. This disbelief gives way to hurt and outrage as the estate thief makes brazen, insincere and false claims to the estate. It's our job as probate and trust litigation attorneys to systematically gather supporting evidence to overcome the actions of estate thieves. Developing these cases often depends on claims of undue influence.
"Undue influence" in California means excessive persuasion that causes another person to act or refrain from acting by overcoming that person's free will and results in inequity. California law considers a number of factors in determining whether an estate transfer was produced by undue influence...

http://www.hackardlaw.com/blog/2017/05/stopping-undue-influence-estate-theft-ca-probate-trust-litigation-attorneys.shtml