Q. I am writing a research paper on the following: RTI and the Law: What every educator needs to know about the history and requirements of the process. Where might I find relevant materials?

For that topic, I recommend going into GALILEO and searching with the following terms:
I would recommend using the phrase instead of the abbreviation, but you can run the searches both ways. I’d also suggest using the quotation marks to search for the complete phrase.

Example searches:
"RTI" and law and education
EDUCATIONAL law & legislation and RTI
"response to intervention" and history
"response to intervention" and requirements
"RTI" and requirements and education
"RESPONSE to intervention (Education) -- Research"

A side note: Typically Galileo is going to supply you with very detailed information on the topic via the articles. You may want to expand your search elsewhere to get a more general overview of the topic. If needed.
Examples:
http://www.rtinetwork.org/learn/ld/legal-implications-of-response-to-intervention-and-special-education-identification

 http://www.rtinetwork.org/learn/what/whatisrti

http://www.rti4success.org/