When you are wondering if you can get online in a coutroom, ask the clerk if their court uses the services of Courtroom Connect. Courtroom Connect provides internet access to the U.S. District Court for the Southern of New York and many other courts. The S.D.N.Y. doesn't allow wifi in its courtrooms, so Courtroom Connect has to set-up a switch to which attorney laptops are connected with an ethernet cable.
The World Wide Web doesn't come cheap in federal courts. You may be charged as much as $40 per day, per individual connection, in addition to installation fees. Courts may restrict the use of smartphones to set up mobile hotspots.