We examine the implications for the viability of multilateral cooperation of di¤erent legal
principles governing how separate international agreements relate to each other. We
contrast three alternative legal regimes: conditionality - making cooperation in one area a
condition for cooperation in another - separation - forbidding sanctions in one area to be
used to enforce cooperation in others - and open rules, i.e. absence of any restriction on the
patterns of cross-issue cooperation arrangements and sanctions. As an example, we focus on
a scenario where countries can enter into selective and separate binding trade and
environmental agreements with di¤erent partners. Our analysis suggests that conditionality
is more likely to facilitate multilateral, multi-issue cooperation in situations where the
environmental policy stakes are small relative to the welfare e¤ects of trade policies; when
the costs of environmental compliance are high, a conditionality rule can hinder multilateral
cooperation. Separation can undermine cooperation by limiting punishment, but can also
promote broad cooperation by making partial cooperation more di¢cult to sustain. Thus,
how di¤erent linkage regimes a¤ect multilateral negotiations depends on the structure of
cooperation incentives for the countries involved.
KEYWORDS: Multilateral Cooperation, Conditionality, Separation, Open Rules.
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