Unions say a plan to enable police to order people in picket lines and blockades to "move on", and arrest those who do not, erodes the right to political protest.

The Coalition introduced reforms on Wednesday extending police powers to issue "move on" orders to people who prevent access to buildings, commit offences in public places, cause others to have a "reasonable fear of violence" or who behave in ways "likely to cause damage to property."

Police would be able to ask such people for their names and addresses, and arrest and fine those who do not comply $720 under the new law. They could also apply to the Magistrates' Court for an exclusion order, banning protesters from entering certain places if they have been given more than one "move on" order in the same place.

ACTU President Ged Kearney said the proposed changes were excessive and unnecessary: "Current legislative provisions governing industrial action are comprehensive and effective for unions and employers."

Employers can apply to the Federal Court to stop unions and individuals from taking unprotected industrial action and personally sue people for pickets which they say harm their businesses.