After a recent story broke about Microsoft and Sony undoing the warranties of opened devices, news has come to light that the practices of jailbreaking and rooting do not invalidate the warranty on one’s phone. 1975’s Magnuson-Moss Warranty Act stipulates that it is illegal for a manufacturer to void the warranty of an electronic device whose software has been altered. Furthermore, the manufacturer has to prove that such modifications directly resulted in malfunctioning hardware.
The main reason that the big companies don’t appreciate rooting and jailbreaking is that it removes some of the direct control they have over your phone. Common arguments against the practice are that is worsens battery life, leaves the phone open to hacking attempts, can ruin built-in features or give users the option of installing stolen or unapproved software. While phones have been exempted from jailbreaking claims since 2010 and smart TVs/tablets were exempted in 2015, video game consoles are still illegal to jailbreak as it was ruled that such devices are used almost exclusively to run pirated software. When the cell industry lost their case in 2010, they changed their anti-jailbreaking tactics to claiming the practice could void a warranty.
While manufacturers have threatened all sort of acts against jailbreakers and rooters that are totally illegal, only a very small portion of their consumer base is aware of what they can do, and what the manufacturers cannot do, within the bounds of the law. While companies cannot void a warranty for jailbreaking your phone, there are certain claims that can still result in problems for your phone. Overclocking a device can lead to an increased level of heat that runs the risk of damaging the device. This is just one of the situations that can lead to indirect invalidation of your warranty; Apple could see that you overclocked your phone and leave you hanging out to dry.
On an unrelated note, most current-day devices have improved their accessibility and interfaces to the point that jailbreaking and rooting offer far fewer benefits than the practice yielded five or even ten years ago. Additionally, users are cautioned that most jailbroken iPhones fail to automatically receive security updates, putting the onus on users, rather than Apple, to keep apprised of new problems.