An insurer who underwrote mortgage-backed securities that failed during the 2008 housing crisis must prove all the elements of common-law fraud in its suit against Countrywide Home Loans, a Manhattan appeals court has ruled.

Ambac Assurance Corp., a financial guaranty insurer, sued Countrywide in 2010 after underwriting 17 residential mortgage-backed securitizations. But Ambac may not point to New York Insurance Law §3105 as a reason for bypassing the need to prove certain fraud elements, an Appellate Division, First Department, panel said Tuesday.