Here is the story to read it brings a bit more details... like the fact the mother...had reached out to the school several times about her concerns and yet the school would not respond to her....
So hell yea I would send a recorder in the back pack to see...
But now makes me wonder why was the school checking her back pack?? Without a cause or thinking the mother was going to prove them wrong they should have not even been looking in the child's backpack!

After charges was brought against her by the school even the judge dismissed it....
The mother should bring charges against the school for not taking care of the situation of her daughter being bullied and instead they ignored her pleas to help.
https://www.washingtonpost.com/news/education/wp/2017/11/28/she-sent-her-child-to-school-with-a-recorder-to-catch-bullies-and-was-charged-with-a-felony/?utm_term=.40bc8061895c
Thanks for this. My first question was going to be for more details, particularly as to why the original incident happened at all.
I have, over the years, seen many cases where the people in authority, reacted by attacking the citizen who showed that they were incompetent and callous, rather than putting their energy in to correcting their mistakes.
I'm glad to see that the justice system actually did try to administer justice, instead of simply going by the letter of the law, and ignore the circumstances.
I hope this doesn't end here. If it is indeed true that the school authorities did ignore reports of bullying, thereby making this approach necessary, as is being reported so far, then the school authorities themselves need to be replaced with people who will do their jobs.
Funny I decided to take some college classed while in my 30's took a recorder to school every day sat it on my desk to record what the teacher said. At times they talked faster then I could write so recording it was the answer. Not only that but it was encouraged by the teachers. So just for thought how is it illegal to tape school work? Regardless if that is what it was used for or not even the Judge found that it was not illegal to do so...I'm a parent I would have done the same thing if they school would not listen to me and take care of the issue....