“In writing” requirement under Art II means that the contract must either be signed by the parties to a dispute or contained in an exchanged of letters or telegrams
By broad interpretation of Article II NYC, arbitration agreements may be deemed valid if they have been entered into by the exchange of telexes and facsimiles, through sales or purchase confirmations or by virtue of a reference to general conditions, if contained in a bill of lading, if concluded through an agent or contained in connected contracts, if concluded pursuant to the trade usages or by means of electronic communication.
Multi-party arbitration causes problems if one of the parties who joined or wanted to join was not a party to the arbitration agreement.