Content:
FTC legal issues re: Tie-in Sales
  and the Magnuson-Moss Warranty Act
Tampering
Consumer Damage
Sherman and Clayton antitrust acts
Third Party and Aftermarket accessories/supplies
Jailbreaking and Rooting your phone or tablet.
FTC Complaints

There are many stories of Dealers and Sellers refusing to honor warranties because people a) Used a third-party ink cartridge, b) Opened their PC to install a memory upgrade, c) Used Prestone antifreeze instead of GM's Dex-Cool® (In their car not their computer), d) Jailbroke their iPhone to use an AT&T phone with Verizon.
I got a lot of email and phone calls after I posted my web page explaining the chemistry of the new antifreezes and whether Prestone OAT was going to cause your radiator to clog.

The Federal Trade Commission (FTC) has guidelines on warranties. Most of the above are related to the tie-in sales clause, Section 102 (c), of The Magnuson-Moss Warranty Act (P.L. 93-637) (1975), which states a manufacturer cannot force you to use a specific item or service (usually one they sell) with their product in order to be eligible to receive a remedy under the warranty.

Tie-In Sales
The Magnuson-Moss act does not have any specific wording about opening or modifying your product, but by "not allowing" you to open your product they are forcing to use their technical support services which is illegal under the tie-in sales clause.

In general, tie-in sales provisions are not allowed. Such a provision would require a purchaser of the warranted product to buy an item or service from a particular company to use with the warranted product in order to be eligible to receive a remedy under the warranty. The following case exemplifies a prohibited tie-in sales provisions: In order to keep your new Plenum Brand Vacuum Cleaner warranty in effect, you must use genuine Plenum Brand Filter Bags. Failure to have scheduled maintenance performed, at your expense, by the Great American Maintenance Company, Inc., voids this warranty.

The Magnuson-Moss Warranty Act states, in part, in Title 15, United States Code, Section 2302, subdivision (c) says,
No warrantor of a consumer product may condition his written or implied warranty of such product on the consumer's using, in connection with such product, any article or service (other than article or service provided without charge under the terms of the warranty) which is identified by brand, trade, or corporate name; except that the prohibition of this subsection may be waived by the Federal Trade Commission (FTC) if -
(1) the warrantor satisfies the Commission that the warranted product will function properly only if the article or service so identified is used in connection with the warranted product, and
(2) the Commission finds that such a waiver is in the public interest.

Consumer Damage:
The federal minimum standards for full warranties are waived if the warrantor can show that the problem associated with a warranted consumer product was caused by damage while in the possession of the consumer, or by unreasonable use, including a failure to provide reasonable and necessary maintenance.
This includes damage from a third party product that did not meet manufacturer specifications.

My google searches did not find any specific "case law" regarding this, but you could go to your library and search the Lexis database to find some.

In the IT (Information Technology) industry and in particular the accessory and upgrade markets, "tie-in sales" ploys can also violate sections 1 and 2 of the Sherman Antitrust Act (1890) which is in Title 15 of the United States Code (U.S.C.) . As the United States Supreme Court has stated:

The essential characteristic of an invalid tying arrangement lies in the seller's exploitation of its control over the tying product to force the buyer into the purchase of a tied product that the buyer either did not want at all, or might have preferred to purchase elsewhere on different terms. When such "forcing" is present, competition on the merits in the market is restrained and the Sherman Act is violated.
Source: Memory and System Warranty - Separating Fact from Fiction - Support - Dataram

Section 3 of the Clayton Act (1914) also has "tying" language.

Sherman was also used in U.S. vs AT&T (1982-84) and U.S. vs Microsoft (1998).

Tampering:
According to Tamper resistance at Wikipedia, "The Magnuson-Moss Warranty Act prevents manufacturers from voiding warranties solely due to tampering. A warranty may be dishonored only if the tampering actually affected the part that has failed, and could have caused the failure.
At "What exactly does your netbook warranty cover? - Liliputing" they say, "ASUS covered one of the screws holding the access panel with a yellow "WARRANTY VOID IF REMOVED" warranty sticker. As pointed out by Cliff Biffle (cliffhacks.blogspot.com), this action violated the Magnuson-Moss Warranty Act with regards to "unacceptable tie-ins."

The same article talks about how Best Buy's Geek Squad refused to fix a hardware problem on a Netbook, for which the user purchased a $80 extended warranty, because he replaced Windows with Ubuntu Linux. He re-installed windows and showed the problem still existed, but Best Buy still refused to honor the warranty.
Note: Best Buy gets the lowest rating for consumer electronics from Reseller Ratings and Consumer Reports .
However, I did see a report of a person getting Best Buy to replace an item by being courteous but persistent, asking to talk to a manager, etc.

Third party ink cartridges:
The "The Magnuson-Moss Warranty Act prevents manufacturers from voiding warranties just because you used a third-party cartridges or a refill kit, but if that cartridge caused the damage it will void the warranty.

See Your Rights | Ink & Toner USA

Using Aftermarket Products:
Magnuson-Moss Warranty - Federal Trade Commission Improvement Act of 1975, protects consumers from being wrongfully denied warranty coverage by new car dealers.

Aftermarket equipment that improves performance does not automatically void a vehicle manufacturer's original warranty, unless the warranty clearly states the addition of aftermarket equipment automatically voids your vehicle's warranty, or if it can be proven that the aftermarket device is the direct cause of the failure.

SEMA (the Specialty Equipment Market Association) will support consumers using products manufactured by their members.

Jailbreaking and Rooting:
Jailbreaking is a term used primarily for modification of the operating (iOS) used in Apples iPhones and iPads to allow it to do things not allowed by Apple or the Vendor (e.g. AT&T or Verizon) selling the device. e.g. Allow an AT&T iPhone to work with Verizon or run apps that were not hosted by Apples app store (e.g. WikiLeaks).

Rooting is the term usually used for doing the same thing on Android phones and tablets.

Originally, jailbreaking was not allowed due to its circumvention of copyright protection systems made illegal by Section 1201 of the Digital Millennium Copyright Act (DMCA) of 1988, which amended Title 17 of the United States Code to extend the reach of copyright.

However, following a request from the Electronic Frontier Foundation (EFF) in 2010, the US Copyright Office granted an exemption, which made it legal. Apple filed comments to this exemption but they were not recognized.

This exemption was a universal act that also applied to Android devices. Therefore, in the US, both processes are legal according to the US Copyright Office.

The current exemption may essentially expire when the Librarian announces the 2012 exemptions, which the EFF expects will happen in October.
See Jailbreaking Is Not A Crime: An interview with Bunnie Huang
and Jailbreaking May Soon Become Illegal Again, Act Now To Help Keep It Legal | Redmond Pie


My Story re: wet tablet:
I got a Samsung Tablet from Verizon wet and opened it up to try and dry it. Verizon replaced it even though they didn't have to.
See Water Damage.

Complaints:
For more information, please contact the Federal Trade Commission in your area:

Atlanta, GA:    (404) 656-1399
Boston, MA:     (617) 424-5960
Chicago, IL:    (312) 353-4423
Cleveland, OH:  (216) 522-4207
Denver, CO:     (303) 844-2271
New York City, NY: (310) 235-4000
San Francisco, CA: (451) 356-5270
Links:
Understanding the Magnuson-Moss Warranty Act (pdf) | Mobile Electronics (www.me-mag.com)
Magnuson-Moss Warranty Act - Warranties - Consumer Laws
PC warranties - The PC warranty and the warranties of individual computer components
Geek Squad Wouldn't Honor My Netbook's Protection Plan - The Consumerist
Keeping Your Mod's Warranty Intact - For Dummies - Aftermarket equipment for cars
Can an automotive dealership void your warranty?
Water Damage

last updated 2 Feb 2012