The Insurance Council is mounting a legal challenge against Christchurch City Council over its rules regarding earthquake-prone buildings.
After the first earthquake in September 2010, the city council raised the minimum seismic strength requirements for all buildings from 34% of the modern building standard to 67%.
The Insurance Council now says that was unlawful.
Manager John Lucas says the change - five months before the February 2011 earthquake which caused much more damage - did not give insurers enough time to adjust their policies to take account of the new rules.
While insurers want to see buildings repaired to a safe standard, Mr Lucas says they should be required to meet only the 34% threshold in effect before the September quake.
