Why cell phone companies are throwing lawyers at each other

Microsoft announced this week that it has inked a deal with Taiwan-based High-Tech Computing (HTC). Under the agreement, HTC will pay royalties to Microsoft for phones that run Google's Android platform. Wait, what? If Google's platform violates Microsoft's intellectual property, why doesn't Microsoft sue Google? Meanwhile, Apple seems to sue other companies only when somebody sues Apple. And why is Nokia suing everybody? The patent system is totally out of control.