Scientists presenting inconvenient facts or ideas that run counter to commercial interests may place themselves at risk of legal action. Frivolous or even vexatious lawsuits are a recognized tool for silencing criticism of corporate or individual commercial interests, particularly where the critics are private individuals or non-commercial entities. Termed SLAPPs, strategic lawsuits against public participation, are meritless defamation or damages actions designed to intimidate and punish scientists and others for speaking in opposition to commercial interests. Such cases are well known and appear frequently in some jurisdictions but are not regularly discussed in scientific circles. Evidence from the US suggests that even the threat of such litigation can stifle public comment and change scientific monitoring and reporting practices. Cases identified as SLAPPs mostly fail in court, but take the intended heavy toll on the defendant, draining energy, time, and money. In this chapter we examine SLAPPs in regard to scientists' involvement in public commentary and provision of scientific information to government and the wider public. Are evidence-based science and the right to speak out in the public interest under threat from SLAPPs? We highlight several known cases and discuss the implications for Australian scientists.