A feature in Drive, with a click of a check box you can disable all the options for viewers to download, copy and print your document.
When it comes to sharing your document, click Advanced in the bottom right and then select ‘Disable options to download, print, and copy for commenters and viewers’. With this selected viewers aren’t even allowed to copy and paste the text!
Sadly viewers are still able to take screenshots of the document, but it’s a great step forward in Drive security.
You can read the full article here.