A child born within 12 months of a woman's most recent meeting with her husband is presumed to be legitimate, since Jewish law believes that in rare cases a pregnancy can last that long. However, if more than 9 months have elapsed and she is known to have been unfaithful then the presumption does not apply. Modern assisted reproductive technology has complicated the issue. Moshe Feinstein ruled that if a married woman is inseminated by sperm from another man the child is not a "mamzer", since it did not result from an act of adultery; Joel Teitelbaum (2005) disagreed, and ruled that since the child is known to be that of a man other than her husband it is a "mamzer".