Editing Known Space (section)

===Organ transplantation===
On Earth in the mid-21st century, it became possible to transplant any organ from any person to another, with the exception of [[Brain transplant|brain]] and central nervous system tissue. Individuals were categorized according to their so-called "[[Transplant rejection|rejection]] spectrum" which allowed doctors to counter any immune system responses to the new organs, allowing transplants to "take" for life. It also enabled the crime of "[[organlegging]]" which lasted well into the 24th century.