Is it legal to record a witnessing conversation without the other person's permission? To find out of the answer, you need to check with your state's laws, as each state has different codes pertaining to this. Here is a link to check your particular state:
http://www.citmedialaw.org/book/export/html/1289
If you live in the state of Ohio, we have a "one party consent" law, which means that only one person needs to consent to the recording of a conversation - even if that one person is the one recording the conversation. This applies so long as there is no expectation of privacy. In other words, do not secretly record someone in their own home or office. But if they are in a public gathering place - park, coffee shop, etc. - the one party consent law applies.
Now, why would you want to consider recording witnessing conversations? Well, for one, to protect yourself. Even police officers do this. If you record your conversations, it will protect you should the person you spoke to decide to launch false accusations against you in terms of something they accuse you of saying or doing.
A second reason is for your own growth or for the equipping of others. You can go back and listen to the conversation to see where things went well, what didn't go well, and maybe how you might answer a question differently next time. You can also use this for the benefit of others, so they can hear what you did and all can grow and learn from your experience.
Do not underestimate this. I have learned so much by watching and listening to hundreds of witnessing conversations involving people like Ray Comfort, Kirk Cameron, Tony Miano, Todd Friel, Trish Ramos, Steve Sanchez, and many others.
You can get yourself a digital recorder for as little as $20 - $30.

