The father of one of the victims of last November's Paris attacks is accusing Google, Facebook and Twitter of offering 'material support' to terrorists. He claims that the companies 'knowingly permitted' terrorists' recruitment, fundraising, and the spread of 'extremist propaganda'. The court papers filed in California state that 'This material support has been instrumental to the rise of ISIS, and has enabled it to carry out numerous terrorist attacks.' The causal link between the companies' support and the attack are relatively weak, however. The tech companies have responded by citing their policies against extremist materials and US law stipulates that Internet companies 'are generally exempt from liability for the materials users post on their networks.'