The word is normally used to show disapproval. When you accuse someone of `stonewalling’ what you mean is that the individual is being obstructive, uncooperative or evasive. The person is delaying taking a decision about something or refusing to answer your questions because there is something he wishes to hide.
*The principal stonewalled when the reporter asked him about the scandal on campus.
Since walls made of stones were difficult to break through, the word `stonewall’ began to be used to refer to anything that presented a formidable obstacle.
The term is also used in cricket. When a batsman `stonewalls’, he spends a lot of time at the crease without really attempting to score runs.