It's not that simple -- employer rights vs employee rights -- especially when things are collectively bargained. What if an employer demanded that you observer religion X and give to certain parties, but you like religion Y and the other party? It seems that you have the option of looking for a job elsewhere. (Then we get into nondiscriminatory laws, etc.).
So employers can only have reasonable demands/requirements as a condition of employment. They can mandate that employees cannot use illegal substances while at work, or even drink alcohol or smoke
while at work. They cannot stop you from drinking your beer at home. Now, since athletes and teams collectively agree to terms, I don't think that Fehr was objecting to an employer's right to say players cannot use illegal substances. The issue was the surveillance and enforcement. What IF a player decided on his own to do something illegal? Let's say only 1 out of 100 did that. The other 99 are forced to give evidence at someone else's time of choosing and conditions and what must be given. Consider how ridiculous the international doping rules have become, where athletes have to tell WADA where they will be AT ALL TIMES so if someone decided to test them, they knew where they were!
I don't think the answer is that Fehr believes players should use illegal substances, or even wishes to promote it. I think he understood that once you accept the idea of random testing, the perfectly innocent and compliant players will have privacy and rights slowly eroded, along with the guys who may wish to cheat the system. Furthermore given that this is a pro sports/entertainment issue, doesn't our Congress have anything better to do than to worry about baseball players relationships with their billionaire owners? We're talking about a few hundred guys here.
I agree with this. Just reminding you though that the NHL wanted linkage between league-wide revenues and player salaries. The players were happy to leave that part out of the CBA.
Now the league has given them an extremely strong incentive to be interested in how they run things--- 57% of revenues are theirs to share.
Edit: Mork beat me to it.