The 1982-D Kennedy Half Dollar is considered a common date, especially if compared to Kennedy Half Dollars from the years 2007-2012. As those years from 2007-2012 had mintages under 2 million for each year.
The 1982-D Kennedy Half Dollar is common up to about MS65 condition. In MS66 grade it is best to buy a graded example, as it only costs a small premium. Examples grading higher than MS66 are very scarce.