What federal legislation allowed prison-made goods to be sold across states lines if the projects compiled with strict rules, such as preventing undercutting the existing structure

The correct answer here is PIECP (Prison industry enhancement certification program.)

Explanation:

This PIECP was authorized under the Justice system improvement act (1979) and Crime control act of 1990, this legislation or program certifies that prison (whether local or state) industry program has meet the required conditions to be free from federal restrain on prison made goods to be sold across the states.