The French, Korean and Spanish version of the Recall animated short state that the Petras Act was signed in 2042. However, that piece of information is confirmed neither in the official version in English nor any other sources.
It is worth noted that this information may be failed. Because based on Chris Metzen's words in Blizzcon 2014 Overwatch Unveiled Panel and Winston's words in Are You With Us?, and one can calculate that the Omnic Crisis started around 2044. It puts the Petra Act's establishment before the creation of Overwatch.