Pro bono publico
The phrase pro bono publico (pronounced 'proh boh noh poo-blick-oh', IPA: /'prəʊ 'bəʊ nəʊ 'pʊb lɪ kəʊ/) is Latin. It means 'for [the] public good', and is often used to describe the work of professionals, such as lawyers, for no profit, and often for no fee at all, because they are performing a public service, or acting in the best interests of the wider community. It is commonly contrasted with paid work: as OED says, "now usually with the implication of no financial recompense".
- In English, 'pro bono publico' can be used as an adverbial ("The lawyer acted pro bono publico in cases of defence against libel suits, accepting no fee") or, less commonly, as an adjective ("The firm does a certain amount of pro bono publico work"). It is usually implied that a person who works pro bono publico is not receiving any financial reward.
In American English, and especially in American legal work, the clumsy three-word adjective is usually shortened to pro bono. This can irritate academics who speak Latin, as 'pro bono' by itself only means 'for [the] good': the most self-interested lawyer is working pro bono [suo] - for her or his own good', or 'in her or his own interest'. This is not necessarily the same thing as the good of the wider community. (See also cui bono.) However, the two-word phrase seems to be gaining currency; and if you do not think your reader is the sort of pedant who uses Latin, there is no reason why you should insist on the three-word equivalent - although it is more accurate.