Key legal question
Whether the disability degree of a self-employed insured person should be assessed by income comparison or by an activity comparison.
Extracted holding
Because the impact of health-related and non-health-related factors on the business results could not be reliably separated, the disability degree had to be determined by a practical activity comparison.
Extracted reasoning
The business had long been affected both by progressive impairment and by structural/economic changes; therefore the hypothetical valid income could not be established with sufficient reliability.