Thurs Sotah 17

If one writes the Megila like a letter (without scratching lines) is passul.

Tosfos points out: even though one is never allowed to write P'sukim without lines, however, I might have thought that B'dieved it checks the woman if she committed adultery. So the Pasuk tells us that it won't take effect at all .

Tosfos is in doubt if the scratched lines can be added after it's written.

Tosfos asks: if you can't write scriptures without lines, why don't one need lines for T'fillin?

Tosfos answers: there is a Halacha L'moshe Misinai that exempts it

R' Tam answers: for writing P'sukim, all you need is to scratch four lines and the four sides of the parchment to make a border. This is needed for T'fillin too. However, Mezuzos and Megilas Sotah needs lines under each written line.