Hundreds of staff at the Federal, Family and Federal Circuit courts, and National Native Title Tribunal are expected to take the half-day industrial action on Friday afternoon as negotiations remain at an impasse.

The strike, unprecedented for court employees, comes after they heaped more pressure on management by handing open letters to people using the courts explaining their rejection of proposed cuts.

Community and Public Sector Union national secretary Nadine Flood said the decision to strike showed how far staff, who have gone four years without a pay rise, were pushed by bosses in enterprise bargaining.

"We've got to this point because the courts bosses are not listening," she said.

"The key issue for our members in this dispute is holding onto their existing workplace rights and job security, and there won't be a resolution until management take their harsh cuts off the table. Courts staff deserve far better than this."

A Federal Court spokesman declined to comment.

Ms Flood said courts staff had received support from the public as they handed out letters, and expected a similar response to their strike.

"This round of bargaining has been traumatic to say the least for people working in the courts and their families," she said.

"Their job security is under threat with proposed cuts to rights while the courts continue to cut staff."

Staff are negotiating a single agreement after the Federal Court of Australia's merger of administration with the Family Court and Federal Circuit Court in 2016.

The Federal Court's public servants responded with a 90 per cent 'no' vote in June to a proposal offering them half the wage rises being paid to their counterparts in other departments and agencies.

The courts staff were asked to accept a new deal that offered an average pay rise of 1 per cent for each of the proposed agreement's three years, cuts to conditions and entitlements and, for some, a longer working week.