There is always a case in which all license will be discriminatory when it comes to "specific fields of endeavor". If the endeavor is to break copyright then a copyright license can't permit that. To take a example, permissive licenses do not allow someone to take full ownership of the copyright of someone else work.
As such the Open Source Definition with the phrase "specific field of endeavor" is limited to cover areas which don't involve copyright law. For many reasons, including copyright law itself, it can not grant that which would be the most broad definition of nondiscrimination.
As such the Open Source Definition with the phrase "specific field of endeavor" is limited to cover areas which don't involve copyright law. For many reasons, including copyright law itself, it can not grant that which would be the most broad definition of nondiscrimination.