Jessica Morley and colleagues raise 16 questions regarding the ethical justifiability of potential COVID-19 tracing apps (Nature 582, 29–31; 2020). Normative reference points for framing the answers need to be considered before we can even begin to address these issues.

For any given app, those answers will vary markedly, depending on whether the evaluation is primarily in terms of individual freedom, public health, solidarity with those most affected by the pandemic, the common good or some other ethical reference point. To guide decision-making, ethical principles must be embedded in a framework that allows us to make them precise and to weigh them up in cases of conflict. Reducing the ethicality of an app to its necessity, proportionality and sufficiency risks sidestepping fundamental debates on how to assess these features.

Morley et al. speak of governments having one chance to get it right. At best, this could induce a false sense of certainty. Ethical reflection involves continuously checking that all arguments have been heard. Introducing contact-tracing apps will be a learning process, not a one-shot game. Instead, we need swift, bold action that builds on democratic institutions, continuous societal discourse and a readiness to fix things if necessary.