text: Top Court Upholds Visa, MasterCard Ruling  WASHINGTON (Reuters) - The Supreme Court on Monday let  stand a ruling that the Visa and MasterCard credit card  associations violated federal antitrust law by barring their  member banks from issuing credit and charge cards on the rival  networks of American Express Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AXP.N target=/stocks/quickinfo/fullquote"&gt;AXP.N&lt;/A&gt; and Morgan Stanley.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=MWD.N target=/stocks/quickinfo/fullquote"&gt;MWD.N&lt;/A&gt;.