1. You're right, it won't. This is actually my suggestion of a cross-driver implementation. The SeleniumDriver doesn't throw an exception, I've provided a possible implementation here: https://github.com/robsquires/MinkSeleniumDriver/commit/c1bdea94208dd12c02772a322e275fdd10f4f3cb

The Sahi driver could be updated to behave in the same way. What do you think about this approach?

2. It's thrown by the php-webdriver as a `WebDriverException` whenever a Selenium2 command fails.