There's been a flurry of good news in the last few days for opponents of the SOPA/PIPA anti-piracy legislation worming its way through the U.S. Congress. The White House has come out opposing key flaws in the legislation, so both versions are effectively stuck for now. Not taking any chances, some of the world's biggest websites, including Wikipedia and Reddit, are going dark on Wednesday, January 18 to protest the ill-conceived anti-piracy legislation.

On American Censorship Day in November, Tumblr censored its users' dashboards. Now other Web behemoths will follow suit, taking their sites offline entirely. For other sites interested in joining the protest, there are technical considerations affecting search engine placement that webmasters should consider. Google's Pierre Far has shared some important tips.

Far's recommendations apply for any intentional, temporary downtime, whether for protest or maintenance. The essential step is to use a 503 HTTP status code, which indicates "service unavailable," for all participating URLs.

That tells Google that the temporary conditions of the pages are not their "real" content, so the search engine won't index them. That will also prevent duplicate content issues, even if the same message - whether it's a word of protest or a message about maintenance - is displayed on all pages.

"Googlebot's crawling rate will drop when it sees a spike in 503 headers," Far says. This is normal, but he says the rate will recover soon for a temporary blackout. For webmasters only blacking out a portion of their sites, Far says they should not change the status code or explicitly disallow crawling in the robots.txt file, which gives Googlebot site-specific instructions. Webmaster Tools will report errors, but this is normal.

Far's bottom-line advice is, "Keep it simple and don't change too many things." You can read his full instructions over on Google+.