Here is a lady who works in these areas and is thinking way ahead.
It might be useful to start thinking, before the war for your mind begins, of ways to protect yourself.
1. Learn how to detect brain reading equipment.
2. Develop the discipline to brain shift. By this, I mean to put your brain into completely different mode in a second's notice. For a Christian, start reciting Bible verses mentally, or sing a hymn in your head. Learn a nonsense phrase and repeat it over and over until you feel you have left the danger zone. Besa me masa (Kiss my grits). If it is a foreign language, that is even better.
3. If you suspect a snoop nearby, start praying, and go through a list of your friends talking to God about their needs.
4. Talk to the eves droppers. Mentally launch a tirade telling the listener what you think of them. Offer to take them to dinner if they identify themselves. Tell them you saw there name in a list of suspects at the police station. Tell them that there is a gorilla standing behind them, then watch to see who looks behind themselves.
5. Carry on a conversation with an imaginary person. Lead the conversation into intrigue of some sort, and then give directions to the spot you are on, and tell the imaginary person on the other end, "When you get here, drop the bomb and blow us all out of here. The snoop will get to go listen to Satan's thoughts in Hell."
You can count on one thing for sure. When the technology to listen to our thoughts starts being used in public places, we will not be told about it in advance. The CIA, IRS, Homeland Security, and the FBI will start using it clandestinely at first.
So, develop a couple strategies for yourself to mess with their toys.