I dont know what happened but ConocoPhillips along with several other Oklahoma companies sued the State is Federal Court saying that the state law limited their ability to comply with the OSH Act's general duty clause. The court agreed and ordered the laws made invalid to the extent that they conflicted with the federal OSH Act. I dont know what happend after that.
They lost... The law was upheld as written when a federal judge at the appeals level essentially told 'em that the OSH claim was BS. That happened at least 2 years ago. It was a big deal and discussed many times here on OSA during the time the thing was being challenged and after the law was upheld and the injunction overturned.
Unless some knothead has recently challenged the law again.