Custom pages have been set up in Lexis and Westlaw to permit searching immigration filings, US Attorney General opinions, and US Supreme Court, 8th Circuit Court of Appeals, and Board of Immigration Appeals decisions simultaneously.
The link should take you directly to the custom search page, but you can also navigate to it from the landing page by looking under the explore content menu, then clicking on custom pages in the far right column.
The link should take you directly to the custom search page, but you can also navigate to it from the Westlaw landing page by clicking on my content, then the custom pages tab, then the Refugee Clinic link.
AILA has a database of sample filings including some briefs. On the left side of the page find the option to filter by Types. You can then limit your search to Amicus Briefs/Alerts and/or Sample Briefs.