Experimental tests of the Bell inequality, beginning with Alain Aspect's 1982 experiments, show that quantum mechanics seems to violate the inequality, so it must violate either locality or statistical independence. However, critics have noted these experiments contained "loopholes", which prevented a definitive answer to this question. This might be partially resolved: in 2015 Dr Ronald Hanson at Delft University performed what has been called the first loophole-free experiment. On the other hand, some loopholes might persist, and may continue to persist to the point of being difficult to test.