In the Chief Justice Corona's impeachment trial, it focuses about the his property that may have come from illegal means like corruption. He was accused guilty of graft and corruption.
In relation to social justice, graft and corruption is very much against it since social justice by definition is "referring to the idea of creating a society or institution that is based on the principles of equality and solidarity, that understands and values human rights, and that recognizes the dignity of every human being" (from http://en.wikipedia.org/wiki/Social_justice).
Considering that corruption violates the aim of social justice for the reason that it does not show equality to the society, then social justice issue is evident.
The money that has been corrupted may have been used to a more productive, useful and helpful projects of the government for the welfare of the many and not just for personal and greedy reasons. This thing makes social justice issue evident in the impeachment trial of Chief Justice Corona.