the medieval mediterranean 87
men and goods, but also the regulation of violence, private or public—in other
words, the definition of the rules of war and peace.
This production of norms followed a double movement: on the one hand, the
development of a legislation specific to each state, regulating trade, navigation or
the status of foreigners; and, on the other (and often in a second phase), bilateral peace
treaties with rules accepted by both sides, at least in times of peace. In Christendom
(both Greek and Latin), these laws were largely inspired by Roman law: this was the
case of the the Rhodian Sea-Law, a collection of Byzantine maritime laws codified
between 600 and 800, or the book of the Consulate of the Sea, written between the
twelfth and fourteenth centuries in the lands of the Crown of Aragon. Quite logically,
these different codes had important similarities, in principle if not always in detail.
Larger differences would be expected with Muslim law, which was seen as a divine law,
based mainly on the Koran and Hadith. But Muslim jurists’ reflection on maritime law
was also widely developed in former Byzantine lands in contact with the Mediterranean
(Syria and Egypt), and was also influenced by Romano–Byzantine law, including the
Digest of Justinian and the Nomos Rhodion (Rhodian Sea-Law). The similarities are
numerous, as Hassan S. Khalilieh demonstrated in his comparison (2006) of the Nomos
Rhodion and the Kitāb Akriyat al-Sufun, a fiqh treaty from the beginning of the tenth
century that incorporated elements of Byzantine maritime law into Muslim legal argu-
mentation. The consequence of this legislation, diverse but partly linked to the same
legal sources and responding to common problems of navigation, is a relative homo-
geneity of the principles regulating maritime activity. This does not mean that the laws
were the same: while the principles were common, the differences could be significant.
Most importantly, since none of these laws was recognized by other states, it is impos-
sible to speak of international maritime law—only of partly-shared legal traditions that
enabled trade. Bilateral treaties, on the other hand, developed rules accepted by both
sides, which required a harmonization of the norms. These became more numerous
from the twelfth century onward, with the expansion first of Italy, then of the Crown
of Aragon, and becoming more and more precise over time. If each treaty was pro-
duced by negotiations between the two states involved and was the result of a certain
balance of power, some rules were common to almost all the treaties, regardless of
context. There again, what was gradually built was a corpus of rules tacitly accepted by
all Mediterranean powers: they set the limits between war and peace, regulated the
sojourn of foreigners and exchanges in ports, facilitated the redemption of captives in
times of peace, and so on. All these treaties made it possible to distinguish, at sea as on
land, enemies from those who were protected by a peace treaty—a fundamental dis-
tinction particularly in legalizing pirate booty but also in ensuring the protection of
merchants in a foreign land. This distinction was never, however, made according to
religious criteria (faithful versus infidel), only by purely political ones (existence or not
of a peace treaty), even while ideology and discourses (and also, in Islam, the Law)
foregrounded these religious distinctions as the basis of Christian–Muslim relations.
This made possible the signing of truces between Muslims and Christians which, regu-
larly renewed, facilitated trade, but also complex alliances between regional powers in
which religious affiliation was just one element of the diplomatic game.
This accumulation of rules, written or tacit, first enabled the development of trade
between merchants of different legal traditions. Commercial contracts, for example,
were sometimes very similar in their principles and probably resulted from influences