Many children at the time of birth may require blood change because of internal complications. Savings of lives of thousands of patients has become possible now because of blood types discovery. Blood types can often be used in legal cases concerning paternity. Though it cannot prove paternity, it can help in making certain exclusions. However blood types cannot be used as evidence in the court of law. The interesting part is the exclusions it can help in making. A blood stain or sample found at the crime scene may not help determine who it belonged to but it can tell who it did not belong to and that can facilitate the investigation. In the cases of paternity...

This is another interesting factor and may help in some cases of paternity. For example a child with blood group O. cannot be linked to a certain man or woman because of blood group because O. is not a dominant blood group. However if the child has a, B or AB as the blood type; then there is strong possibility of determining paternity. One of the parents must have that blood type.
Karl Lansteiner's discovery has opened new avenues of research in the medical field. This research could have never been possible without the knowledge we now have concerning blood types.