His reasons for stating that eyewitness testimony was not reliable are very basic, His many reasearch expierments proved that different individuals viewed the same situation in different ways and interpreted them differently and when many eyewitness were put on the stand their contradicting testimonies would either confuse the jury or the fact that they have forgetten or misinterpreted key details that could make or break a case.  Today there is a "general acceptance" for eyewitness testimony but in many cases it is questioned and does not hold up, but the testimonies creditablity really depends on the case's individual circumstances.