Milestones

? Easy Rider. California motorcyclists won't have to wear helmets after all, thanks to Gov. George Deukmejian's veto of the first mandatory helmet law to make it through the legislature during a 20-year struggle over the issue. (See Editorials, Aug./Sept.)

? Crash barrier. Program trading and portfolio insurance caused last October's stock market crash, right? Wrong. (See Editorials, Jan.) In fact, argues UCLA economist Richard Roll in Black Monday and the Future of Financial Markets, computer-directed trading may have kept the market from falling even further. Roll looks at all 23 major world stock markets and finds that the five markets with such trading dropped 6.6 percentage points less than the others.