When an attorney works for a client with no fee, this is known as what?

When an attorney works for a client without charging any fees, this is referred to as pro bono work. The term "pro bono" comes from the Latin phrase "pro bono publico," which means "for the public good." This practice allows attorneys to provide legal services to individuals or groups who cannot afford to pay for them, thus ensuring access to justice for underserved populations.

Pro bono work is often seen as part of an attorney's professional responsibility and commitment to the community. Many law firms and legal organizations encourage their attorneys to take on pro bono cases as a way of giving back and supporting those in need.

The other options listed refer to different arrangements or concepts in legal practice. Contingency refers to a situation where an attorney only gets paid if the case is successful, with fees typically being a percentage of the awarded amount. A retainer is an upfront fee paid to secure an attorney's services, while a fee waiver usually pertains to the court’s decision not to require a fee for legal filings due to a party's financial status.