Can condo association president obligate future board to new vendors?

Is it legal for a Condominium President to sign contracts with vendors and employees obligated the future board and the association without a board of directors vote? Our past president signed an employment contract with management 3 weeks before his reign was up. This document has no witnesses and was back dated. Also, a (3) year contract was signed with Comcast. Both of these contract were signed without board approval. Can the current board sue the past president and file a claim under the Errors and Omissions Policy?