To win phase one of the two-phase anti-SLAPP analysis, the defendant must show their conduct arose from constitutionally protected activity. This rule refers to exercising (1) the petition for redress of grievances, or (2) free speech, made in connection with “…a public issue or an issue of public interest.” 
However, the anti-SLAPP law does not define “public interest” or “public issue.” As one court noted, “Those terms are inherently amorphous and thus do not lend themselves to a precise, all-encompassing definition.”  Nevertheless, there are general guiding principles courts follow to determine whether a statement concerns a matter of public interest.
First, section 425.16 is to “‘be construed broadly’ to safeguard ‘the valid exercise of the constitutional rights of freedom of speech and petition for the redress of grievances.’”  The legislative history and case law “suggest that ‘an issue of public interest’ … is any issue in which the public is interested. [emphasis in original]. In other words, the issue need not be ‘significant’ to be protected by the anti-SLAPP statute—it is enough that it is one in which the public takes an interest.” 
Second, section 425.16 “governs even private communications, so long as they concern a public issue.” 
Third, there exist “three non-exclusive and sometimes overlapping categories of statements that have been found to encompass an issue of public interest under the anti-SLAPP statute[:]” (1) “cases where the statement or activity precipitating the underlying cause of action was ‘a person or entity in the public eye[;]’” (2) “the statement or activity involved ‘conduct that could directly affect a large number of people beyond the direct participants[;]’” and (3) “cases where the statement or activity involved ‘a topic of widespread, public interest.’” 
Finally, five additional attributes of an issue would make it one of public, rather than private, interest. (1) ‘“public interest’ does not equate with mere curiosity[;]” (2) “a matter of public interest should be something of concern to a substantial number of people[;]” (3) “there should be some degree of closeness between the challenged statements and the asserted public interest[;]” (4) “the focus of the speaker’s conduct should be the public interest rather than a mere effort ‘to gather ammunition for another round of [private] controversy[;] and (5) a “person cannot turn otherwise private information into a matter of public interest simply by communicating it to a large number of people. 
In summary, in this first phase of a court’s anti-SLAPP analysis, the defendant must show their statements or activity arose from a First Amendment-protected petition for redress of grievances or from the exercise of free speech. Noted above are some analyses courts use to determine — as required by California’s anti-SLAPP statute – whether the allegedly offensive activity emerged from a public issue or a matter of public interest.
Note that even if defeated in the first phase of this judicial analysis, a defendant can still prevail (defeat the special motion to strike) entirely on the second.
 Cal. Civ. Proc. Code §425.16 (e)(3)-(4) – All further references are to the CCP unless otherwise noted.
 Cross v. Cooper, (2011)197 Cal. App. 4th 357, 371
 Nygard, Inc. v. Uusi-Kerttula, (2008)159 Cal. App. 4th 1027, 1039 (quoting Cal. Civ. Proc. Code §425.16(a))
 Id. at 1042
 Wilbanks v. Wolk, (2004) 121 Cal. App. 4th 883, 897 (citing Averill v. Superior Ct., (1996) 42 Cal. App. 4th 1170, 1175)
 FilmOn.com v. DoubleVerify, Inc., (2017) 13 Cal. App. 5th 707, 717 (citations omitted)
 Weinberg v. Feisel, (2003)110 Cal. App. 4th 1122, 1132-33