When an employee leaves for a competitor, the dispute rarely proceeds to trial. It is resolved at the preliminary injunction stage, quickly, and the ruling usually determines the commercial outcome regardless of the eventual merits.
Speed cuts both ways. An employer that waits weeks after learning of the departure undermines its own claim of irreparable harm. One that moves within days signals that the harm is real.
Irreparable harm is the contested element. Lost revenue is compensable in money and therefore not irreparable. What is argued instead is loss of customer relationships and goodwill, and disclosure or use of confidential information — harms that resist measurement. Concrete evidence matters far more than assertion: a customer who has moved, a download of files before resignation, a solicitation email.
Forensics decide many of these cases. Access logs, mass downloads to external drives, and cloud sync activity in the final days of employment are the most persuasive evidence available and are often the reason an injunction is granted.
Bonds. A party obtaining an injunction is generally required to post security, and where the injunction stops someone earning a living the amount can be substantial.
For the departing employee: what you take matters more than where you go. The cases that go badly are almost always the ones involving copied files.