Unasa Iuni Sapolu said the vehicle-based procession went 30 kilometres from Faleolo Airport to parliament.
They were raising concerns over proposed law reforms many say are unconstitutional and unwarranted.
"People must stand up for their freedoms and rights which are going to be affected by these three bills," said Unasa.
Because of Covid-19 distancing measures the protesters took to their cars and trucks.
Unasa said despite not being well publicised, there were over 50 vehicles with more than 100 people when they reached parliament.