Act of Necessity is an Australian 1991 television film about a couple who believe their daughter's cancer is caused by chemicals. It was the fifth in a series of docu-dramas about social issues made by Film Australia. It had an improvised script and features actors working alongside actual people form government, law and medicine. It culminated in a trial before a real judge and the outcome was not known until the judge made his ruling.

The film looks at the potential dangers from chemicals used on cotton crops. The Australian Cotton Foundation and the Aeriel Agricultural Association of Australia both tried to get it banned.