Christian Democratic Party leader Reverend Fred Nile has admitted making a significant error in a horror story he told during the NSW parliament debate on voluntary assisted dying laws.

But Mr Nile has put down the error to possible divine intervention after he experienced "a full blown visual" of a newspaper report of the story he incorrectly recounted.

During the marathon debate in the upper house that saw the bill defeated 20 votes to 19 on Thursday night Mr Nile said he had read case studies from the US state of Oregon on whose laws the proposed legislation was based.

"In a published and certified incident a patient signed a consent form that she wanted a lethal injection from her doctor to terminate her life," Mr Nile explained.