Canonical Tag Not Yet Reliable

I’m a big fan of the new canonical tag (er, element, to be more technically correct). It’s a powerful tool for dealing with duplicate content. But it’s not exactly reliable yet. Google wants us use it as if it were. Unquestionably, it’s a signal. But it can be ignored, even when it should clearly by obeyed.

Case in point: Many thousands of non-canonical URLs are indexed. For example click on some of the listings on
this SERP and compare the URLs you were led to by Google to what’s listed as the canonical URL in the HTML source of these pages. You’ll see that the parameters OPC and PFM are present in the URLs in the search listings but are not present in the canonical link element. Hmmm.

I know Google uses the element as a strong hint rather than an absolute directive, however it sounded like from Matt’s video that it’s about as strong a hint as a 301 redirect. If that were the case, I wouldn’t have expected to see this behavior. This example I found doesn’t look to me to be an “edge case,” and I don’t see any reason why Google shouldn’t trust or adhere to the canonical tag in this particular situation. So what gives?

If you’re thinking that perhaps the canonical tags were just added and didn’t have time to kick in yet, take a look at the Cached links on some of those search listings. Some of these pages were cached way back in March and yet still have the canonical tag present in the Cached version. Certainly 2+ months is ample time for Google to canonicalize these pages??

I like canonical tags and I use them. But I always prefer 301 redirects over canonical tags, as 301s are pretty much *always* obeyed.

The lesson here: I wouldn’t bet my business on the canonical tag being obeyed by Google.