This may be due to personal tastes or ethical reasons.

The study was stopped for ethical reasons to give the placebo group the same treatment.

For ethical reasons, the test cannot be performed in people.

I see no ethical reason for taking a different attitude toward women.

Indeed, they could not deny this one, for either ethical or personal reasons.

Three studies were stopped ahead of schedule for ethical reasons because those given early treatment seemed to benefit.

But we don't see any ethical reason not to run it.

There is no ethical reason why you should not use it.

This choice was made for religious, political, magical, ethical and social reasons.

It is always best to do these things for ethical reasons.