Legal Question in Civil Rights Law in Iowa

The sign or lack of it is not relevant. Iowa Code section 727.8 says:

727.8 Electronic and mechanical eavesdropping.

Any person, having no right or authority to do so, who taps into or connects a listening or recording device to any telephone or other communication wire, or who by any electronic or mechanical means listens to, records, or otherwise intercepts a conversation or communication of any kind, commits a serious misdemeanor; provided, that the sender or recipient of a message or one who is openly present and participating in or listening to a communication shall not be prohibited hereby from recording such message or communication; and further provided, that nothing herein shall restrict the use of any radio or television receiver to receive any communication transmitted by radio or wireless signal.

There are matters that take place in the courts that are of a private or sensitive nature, in particular cases involving children, sex abuse offenses, or jury deliberations.

Such an effort might be seen as an effort to unduly influence a jury or huniliate persons for some ulterior reason.

There may also be local rules that prohibit what you're proposing.

If this is something you wish to pursue I would suggest you submit your request to the chief judge in your judicial district.