&gt; As the California Supreme Court made clear, federal law (which permits monitoring with the consent of one party) does not preempt more restrictive state eavesdropping laws, even when the monitored communications are interstate.  Accordingly, companies that monitor interstate calls for quality control purposes must consult the applicable provisions of state, as well as federal, law. (o)<p>i feel another commenter, em3rgent0rdr, may have indirectly answered my confusion by stating:<p>&gt; Even if judges prohibit such evidence on the grounds of it being illegally obtained, you will still find that prosecutors will use that evidence to find other evidence and for constructing a case that doesn&#x27;t use that illegally obtained evidence. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Parallel_construction" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Parallel_construction</a> (i)<p>(o) <a href="http:&#x2F;&#x2F;www.mofo.com&#x2F;resources&#x2F;publications&#x2F;2006&#x2F;07&#x2F;california-two_party-consent-law-applies-to-reco__" rel="nofollow">http:&#x2F;&#x2F;www.mofo.com&#x2F;resources&#x2F;publications&#x2F;2006&#x2F;07&#x2F;californi...</a><p>(i) <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11699146" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11699146</a><p>.. completely offtopic, but how unfortunate is that lawfirm&#x27;s domain?