Enroute Controller notified of a loss of separation event during multiple weather deviations and pilot non adherence to turn directions; voiced concern regarding the facility's reluctance to file a pilot deviation in this case.

Narrative

This situation should raise red flags when it comes to this Center's handling of a pilot deviation; and a serious safety issue that is being swept under the rug for no apparent reason. I was working Sector 1. The sector had up to extreme weather in numerous areas and almost all aircraft were deviating. I took a hand off on CRJ2 east of ZZZ1 at FL300. He needed to deviate west for weather. I issued the clearance; 'deviation west approved; when able precede direct ZZZ2'. A few moments later I took a hand off on a C560 just south of ZZZ3 at FL320 landing ZZZ4. In the fourth line of the Data Block was 'DR/ZZZ5'. (Deviating right; direct ZZZ5 when able). After a few miles into my airspace; the C560 requested lower. He had been right of course the whole time; and by the time he made this request; had he turned direct ZZZ5; he would have had more than standard separation from CRJ2. I descended the C560 to FL300 due to northbound traffic southeast of him at FL290. I could descend the C560 further as soon as he passed the FL290 traffic thus making the traffic with the CRJ2 even less a factor. The C560 turned left of course and [was] head on with the CRJ2. When I realized the situation; I issued a clearance to the C560 to turn 20 degrees right for traffic; the two aircraft were still about 12 miles apart. The C560 responded with 'unable due to weather'. There was no weather there; and in fact the aircraft at FL290 was off his right front. I was told later that he indicated there was an overhang he wanted to avoid. I descended the aircraft at FL290 to FL280; turned the CRJ2 15 right; there was a severe weather echo off his right so I was glad he turned at all; and descended the C560 to FL290; I told him to expedite and give me a report. I'm not sure if the CRJ2 did actually turn the full 15 degrees. The C560 stayed level for at least 2 RADAR hits before a descent was observed; and separation was lost. I was told that they came within 3.9 miles and 700 FT. I asked the C560 if he was left of course and he responded in the affirmative. I told him that he only had clearance to deviate right. He told me that he was given no restriction on the direction of turn. A few minutes later he said that he was first cleared left; then right and assumed he could go back to the left. All of those transmission occurred in another area. Right after the incident; the tapes were pulled; printouts were made of the track of the C560; and it was declared an obvious pilot deviation. When I came back to work the next week; I was told that they had changed this to an operational error and it was not a pilot deviation. I just watched the tape of the incident with my Supervisor. I have been an Air Traffic Controller for over 20 years and have never witnessed such dereliction of duty. If a pilot is cleared to only turn right; and he turns left; how does this Center say this is not a deviation? I was told by my Supervisor that he wanted to file this as a pilot deviation and an operational error; but that the facility manager decided that the pilots actions were not worthy of a deviation status. I can't help but wonder if this pilot is being protected. The Supervisor then said that we were just trying to learn from this situation. I turned to my Supervisor and told him that the purpose of this meeting was to promote safety; and you have decided that a pilot ignoring two air traffic clearances; was no safety concern whatsoever; and yet a controller is somehow at fault. If this is how this Center is going to handle pilot deviations; our airspace is going to be a very dangerous area to fly through.