What is the test for success in an anti-SLAPP motion?

Our Supreme Court clarified recently: "The first step of the anti-SLAPP analysis is limited to whether a claim arises from protected activity. We made it clear in Flatley [,supra, 39 Cal.4th 299] that conduct must be illegal as a matter of law to defeat a defendant's showing of protected activity. The defendant must concede the point, or the evidence conclusively demonstrate it, for a claim of illegality to defeat an anti-SLAPP motion at the first step." (City of Montebello v. Vasquez (2016) 1 Cal.5th 409, 424.)