Steve Jobs threatened to sue Palm if its CEO did not stop attempting to hire Apple employees, according to emails released by an American court.
Jobs told Palm's Ed Colligan in 2007 that his employees were being "actively recruited" by the company, and "we must do whatever we can to stop this".
"I'm sure you realize the asymmetry in the financial resources of our respective companies when you say: "We will both just end up paying a lot of lawyers a lot of money"," Jobs continued.
The email was among others released as part of a civil lawsuit brought by five tech workers against Apple, Google, Intel and others, which alleges Silicon Valley executives conspired to stop cross-hiring of employees.
The email, published by the Verge, was supported by Colligan's sworn statement which claims Jobs "proposed an arrangement between Palm and Apple" to stop hiring each other's employees.
"Mr. Jobs also suggested that if Palm did not agree to such an arrangement, Palm could face lawsuits alleging infringement of Apple's many patents," Colligan said in the statement.
The lawsuit says this attempt successfully stretched across Silicon Valley, working to suppress wages, possibly by millions of dollars and making it difficult to switch jobs.
The companies involved had attempted to keep the documents secret, but this was rejected by US District Judge Lucy Koh.
The emails released so far appear to show how top executives tried to resist other companies from poaching their employees.
One email shows that Steve Jobs asked Google's Eric Schmidt directly to stop hiring Apple workers.
"I am told that Googles new cell phone software group is relentlessly recruiting in our iPod group. If this is indeed true, can you put a stop to it?" Jobs asked.
In another exchange, Schmidt replies to a Google staffing strategist's decision to terminate a recruiter for pursuing an Apple employee, saying it was an "appropriate response".