This surprised me because, as far as I know, prayer is legal. You can pray your face off in this great nation any time you want to. You can bow towards Mecca if you're a Muslim; you can grasp a rosary if you're Catholic; you can bawl to Jesus at the top of your lungs if you belong to a religion that requires you bawl to Jesus at the top of your lungs. Nobody will stop you, unless you're actively disturbing the peace.
Nobody knows if praying works, although most of the evidence indicates not. Most everybody would have won the lottery by now if it did, and most if not all sports teams would be undefeated.
Of course, truly sincere prayers do not ask for divine help in winning the lottery or for a grand slam in the bottom of the ninth. A devout person prays whether he or she has any requests of God or not, but even in these supposedly unselfish prayers there lurks the hard core of self-interest—when that believer is in his or her final moments, when they are snared in the Swamp of Doom and the Crocodile of Fate starts munching on their leg, they want God to recognize their number when it pops up on His Heavenly Caller ID.
When you pray, you are asking the being whom you believe to be the Creator of the Universe to stop whatever He is doing and grant you, a tiny, temporarily conscious bag of moisture among billions of similar bags of moisture in a remote region of an average galaxy among millions of others, His attention. A really sincere prayer should begin "Oh Lord, I know you probably have a couple quasars in the oven right now," and then follow it up with whatever insignificant request you have of Him, whatever it may be, say for your dog to be cured of cancer or to for you get through tomorrow's job interview without wetting yourself.
Whether you get what you pray for or not, it is against the rules for you to bitch to God. It is incumbent upon you, the prayer, to be grateful to Him every time you catch a break, and to realize it is not His negligence, but rather some fault in yourself that makes God laugh off your prayer and leaves you to endure the merciless screwing you were beseeching Him to avoid.
All of this is legal, as legal as having a pet mosquito, although it may well be as pointless. So when you wear a t-shirt that says "Legalize Prayer," that is not what you really mean. What you want is for me to listen to you pray, or possibly you want to force me to pray along with you, in school, at public meetings, before sessions of the legislature, wherever.
This will not help either of us. God will not listen to you any better because you are boring the crap out of me and any other non-Christian or nonbeliever you have succeeded in making your audience while you beseech Him. In fact, He is probably being distracted from granting you your prayer by being forced to listen to mine, the only one I ever utter:
"Oh, God, please let this be over sometime soon!"
Oddly enough, my prayer is always granted.