In 1974 he was recruited into the Moonies after a failed attempt to rescue his sister Catherine from the cult, but after eight months he left, and instead joined his mother's anti-cult crusade.

Kendrick Moxon, Scientology's lead counsel gathered information on Greene as part of what he termed a "simple, standard check".

[9] Greene also successfully represented client Raul Lopez against the church; Lopez had sustained partial brain damage in an auto accident and turned to Scientology, subsequently donating or "investing" most of his 1.7 million-dollar accident settlement money to the church.

(Paul Morantz, in an amicus curiae on behalf of the Cult Awareness Network, also briefed and argued the case.)

In 1988, the state high court held that religious organizations may be sued for fraud and intentional infliction of emotional distress when they use deception to cause candidates for recruitment to unwittingly expose themselves to brainwashing techniques.

In a legal opinion written by Justice Stanley Mosk regarding tactics religious groups use to attract followers, the court found that any burden on the free exercise of religion was outweighed by the state's interest in protecting against "fraudulent induction of unconsenting individuals into an atmosphere of coercive persuasion" because many people exposed to brainwashing techniques without their knowledge or consent would develop serious and sometimes irreversible physical and psychiatric disorders, up to and including schizophrenia, self-mutilation, and suicide.

[12] In 1998, in Bertolucci v. Ananda Church of Self Realization, Greene won a US$1.625 million jury verdict for fraud, coercion and sexual exploitation of a woman devotee.

[1] From 2003 to 2005, Greene was involved in a controversy about a changeable "Freedom" sign with political messages on the side of his San Anselmo law office, facing eastbound traffic on busy Sir Francis Drake Blvd.

Greene settled the dispute in October 2005 by agreeing to use only half the space for messages, and was reimbursed by the town for nearly a thousand U.S. dollars in expenses.

[1][13] In November 2005, Greene ran for a seat on the San Anselmo Town Council against Ian Roth, but came 300 votes short of being elected.

Greene stated he would "continue on the same path, emphasizing open and responsive government and looking at planning and regulatory codes to make them more accessible and friendly to residents of San Anselmo".

He was the only seated councilman to speak against the proposal to turn a San Anselmo park into a flood basin, and a citizen-emplaced ballot measure supported by Greene that was designed to prevent the flood-basin proposal also won,[neutrality is disputed] despite opposition by Marin County political figures.

Regarding his opponents, Greene said that "I'm very grateful for the intelligence and good judgment of the San Anselmo voters, who were able to see through a very well orchestrated, unified and negative campaign.