Law of Independent Assortment was stated by Gregor Mendel.
This law very simply states that during the formation of gametes the segregation of one pair of alleles is completely independent of the other pair . This gives an equal chance to both of them to present themselves. This would also mean that a particular character/ trait shows itself independent of other pair.
EXAMPLE- A dihybrid cross as in figure below. Observe that how color and shape traits have separated independently.