You don't necessarily need to see a lawyer. Everything you write is automatically protected by copyright ( in Canada, at least ). The burden then is to prove that you have written the document.
Here is a trick learned in a class,
1. Print out the document you want to prove that you have written.
2. Sign every page.
3. Send it to yourself via registered mail.
4. Do NOT open the envelope.
When somebody challenges that you have authored a document, you can use the sealed envelope to prove that you authored the document at that given date. Since it bears the stamp and date, you can at least show that you have created the documents in that day.
If you have a website or dynamic content, you just update your envelopes periodically.