John W. Sansing, 48, a brilliant criminal defense lawyer who became a journalist and the executive editor of Washingtonian magazine, died Friday of infectious colitis at his Washington home. Mr. Sansing was involved in some of Washington's most notorious criminal trials in the 1970s and won some notable acquittals. As a reporter, he wrote about his experiences at the bar in a way that illuminated the workings of the court system and how it affected the life of the city. Mr. Sansing's last article appeared in 1990. It was headlined, "First, Kill All the Lawyers," and suggested that Washington would be better off with only half as many lawyers as it had.