A world first opt-out union membership system is being proposed for New Zealand.

The idea from four academics would see workers signed up to a union at the same time as they sign their employment contract.

Waikato University Management Professor Mark Harcourt told Heather du Plessis-Allan that right now, the system is opt-in, which makes it hard for unions to gather members who are afraid of offending their new employer.

He says people can still choose to be part of a union, or not part of a union, under an opt-out system.

Harcourt says research shows widening income inequality is linked to the decline in union presence.

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