Employee privacy and image use

My concern is about employee privacy and image use. Since it is so easy to take a picture these days, and many employee meetings are happening over videoconference, what are the laws governing the use of employee images and materials generated by a library employer?   What stops the participants in an online meeting from taking and using screenshots of attendees?  I know that being a librarian often means working with the public, but when it comes to an employer using an employee's picture and other digital captures of their image, what does the law say?   Can an employee attending an online meeting be compelled to turn on their camera?