The NSW Bar Association has criticised the state government's crackdown on animal rights activists as "harsh and disproportionate", warning it could see people jailed for peacefully protesting on public land.

Proposed laws, known as the Right to Farm Bill, will be scrutinised by an upper house inquiry on Thursday, amid concerns protesters could face fines of up $22,000 or three years in jail.

In a submission to the inquiry, the state's peak body for barristers reinforced concerns held by environmental groups that laws could criminalise protests that have nothing to do with farming.

The association concluded there were "significant issues" with the bill, including the fact "very large increases in penalties are proposed", which were "likely to discourage people from exercising their right to peacefully protest."

"In view of the nature of the offence, imprisonment is a harsh and disproportionate penalty," the submission said.