  We study community structure in time-dependent legislation cosponsorship
networks in the Peruvian Congress, and we compare them briefly to legislation
cosponsorship networks in the US Senate. To study these legislatures, we employ
a multilayer representation of temporal networks in which legislators in each
layer are connected to each other with a weight that is based on how many bills
they cosponsor. We then use multilayer modularity maximization to detect
communities in these networks. From our computations, we are able to capture
power shifts in the Peruvian Congress during 2006--2011. For example, we
observe the emergence of 'opportunists', who switch from one community to
another, as well as cohesive legislative communities whose initial component
legislators never change communities. Interestingly, many of the opportunists
belong to the group that won the majority in Congress.
