The pipeline has drawn more critical attention than its corporate sponsors seemed to expect, and it is important to understand why that happened. Keystone is a bad deal for the American taxpayer on the merits, but that’s not the only reason. More important, environmentalists have decided that enough is enough.

We saw plenty of important decisions made during the Bush era in the name of “streamlining,” “cutting red tape” or “using sound science” — that is, science funded by an industry that wanted less oversight. In November 2008, millions of Americans breathed a sigh of relief and told themselves those days were over. Keystone has rallied the entire environmental community because it is a visible and sometimes painful reminder of the way things were done under Mr. Bush.

The administration’s approach to the pipeline is a throwback to the time when endangered species were defenseless in the face of corporate moneymaking. It is a reminder that even though our environmental laws use science, not profits, as the basis of our environmental decisions, any company with bottomless pockets used to be able to game the system and get away with it.

That’s why Keystone is about more than one pipeline. It is about establishing once and for all whether we have moved on from the disastrous Bush-Cheney view of environmental policy. President Obama’s own Environmental Protection Agency has said in no uncertain terms that the pipeline will contribute significantly to greenhouse gas emissions. That should be the end of the conversation. The fact that it isn’t — that we’re left hanging and hoping — is more than disappointing. It is a very troubling sign for the future.

As the news media has reported widely, the contractor chosen by the State Department to assess the pipeline’s environmental impacts violated federal conflict-of-interest rules to get the job, and nothing has been done about it. That company, Environmental Resources Management, did work for TransCanada, Keystone’s parent company, in the recent past and told the State Department the exact opposite on disclosure forms that anyone in the world can now read for herself. A report on Wednesday from the State Department inspector general, which many outlets covered as though it exonerated the department and E.R.M. of wrongdoing, is actually an important example of the problem. The I.G. only looked at whether the department followed its existing process for choosing a contractor. It should have looked at whether that process produces reliable outcomes.