After graduating from Duke University Law School in 1977, John Zamer joined longtime Atlanta firm Hansell & Post and embarked on a career advising clients in major transactions. One of his most significant deals occurred 12 years later, when, at age 37, Zamer led the team that negotiated Hansell & Post's merger with Jones Day, said to be the largest law firm merger at the time.

Throughout his four decades in corporate law, John represented numerous high profile clients on some of their most important transactions. A few highlights include: the leveraged buyout of Georgia Gulf Corp. from Georgia-Pacific in 1984, its IPO in 1986, its successful defense of a hostile takeover attempt in 1990 and finally its $2.4 billion sale to Westlake in 2016, following another hostile takeover attempt.