  In this work, we examine how fact-checkers prioritize which claims to
fact-check and what tools may assist them in their efforts. Through a series of
interviews with 23 professional fact-checkers from around the world, we
validate that harm assessment is a central component of how fact-checkers
triage their work. We also clarify the processes behind fact-checking
prioritization, finding that they are typically ad hoc, and gather suggestions
for tools that could help with these processes.
  To address the needs articulated by fact-checkers, we present a structured
framework of questions to help fact-checkers negotiate the priority of claims
through assessing potential harms. Our FABLE Framework of Misinformation Harms
incorporates five dimensions of magnitude -- (social) Fragmentation,
Actionability, Believability, Likelihood of spread, and Exploitativeness --
that can help determine the potential urgency of a specific message or claim
when considering misinformation as harm. The result is a practical and
conceptual tool to support fact-checkers and others as they make strategic
decisions to prioritize their efforts. We conclude with a discussion of
computational approaches to support structured prioritization, as well as
applications beyond fact-checking to content moderation and curation.
