You need strong evidence to win a lawsuit for defamation in Oregon.
And you must act fast. The short one-year statute of limitations alongside the complex legal framework (including the Anti-SLAPP statute) means that acting fast is critical to a plaintiff's chances of success.
Admissible evidence for libel is generally easier to obtain than evidence of slander, and may include screenshots, messages from social media, emails, text messages, and other documentation of written materials. Documenting slander generally requires interviewing the individual(s) who heard the defamatory statement and reducing their observations to writing in an admissible form. An attorney can help you with that.
It may also be necessary to provide a spoliation notice to third-party companies who may be in possession of evidence relating to the defamation to ensure that the take action to avoid losing or deleting evidence that may be necessary to your case.
In an action for defamation where a malice standard is involved (such as defaming a public figure or in certain Anti-SLAPP cases involving accusations of sexual assault) additional evidence demonstrating that the defendant knew or had good reason to know the falsity of their statement should be secured at the earliest opportunity.
In cases involving media publishing defamatory information, a retraction must be demanded under ORS 31.215, generally within 20 days of learning of the publication, and the unique issues involved in suing a media defendant requires gathering additional evidence of negligence.