The Green Party says Government changes have resulted in a backlog of appeals before the District Court against decisions by the Accident Compensation Corporation (ACC).
New figures show 829 people have waited longer than six months to have their appeals heard.
The Green Party's ACC spokesperson, Kevin Hague, says it has become harder for accident victims to get cover since the National Party took office.
He says the District Court overturns about 40% of ACC decisions.
Mr Hague says an independent review of changes at the Corporation is needed.
ACC Minister Nick Smith says the overall number of appeals has not significantly changed in the past five years.
He says the majority are found in ACC's favour, so he doesn't believe it supports an inquiry.