Any legal issues hinge, as the author hinted, on a court inventing a relevant market here. The Clayton Act (and specifically 15 U.S.C. section 14 on tying), like other antitrust laws in this country, requires that the tying either create a monopoly or "substantially lessen competition...in any line of commerce". Simply lessening competition is not illegal, it has to be on the scale of affecting the entire line of commerce, aka relevant market.<p><a href="http://www.law.cornell.edu/uscode/15/14.html" rel="nofollow">http://www.law.cornell.edu/uscode/15/14.html</a><p>If a court decides that in dealing with App Store sales, we're talking about the software market, then the App Store is such a tiny piece of the software market that literally no policy they set can SUBSTANTIALLY lessen competition in the entire market. It's a private company so they're free to set whatever policies they want. If they want to tie their browser to their phone and prevent you from using anyone else's browser, that's completely legal.<p>A court would have to really stretch and define something very narrow, like a smartphone application market, to even begin arguing any antitrust case.