President Obama’s decision on Wednesday to dismiss the acting commissioner of the Internal Revenue Service was a largely symbolic demonstration of anger and authority. The official, Steven Miller, was not directly involved in the misguided decision to single out Tea Party groups for special scrutiny in granting tax exemptions. What is more important is Mr. Obama’s promise to clarify the extremely vague tax laws, which are the root cause of the problems in both the I.R.S. and the political system.

The report issued Tuesday by the Treasury Department’s inspector general said no one outside the I.R.S. had pressured staff members to look more closely at Tea Party groups. The agency’s mistake was made in-house, and the report uncovered no evidence that it was the result of political pressure from the White House, as many Republicans are charging.

Instead, it was a group of midlevel employees who decided to search for the phrase “Tea Party” and other key words used by conservative groups in identifying and evaluating applications to become tax-exempt “social welfare” groups. Conservative groups were questioned, rejected or left pending with no decision. Those employees “did not consider the public perception of using politically sensitive criteria when identifying these cases,” the report said, adding that “ineffective management” allowed this poor decision-making to go on for 18 months.

The practice was inexcusable, because social-welfare groups of all political stripes, known in the tax code as 501(c)(4) organizations, had for years abused their tax exemptions through excessive political activity, and the I.R.S. should have cracked down on them without regard to ideology. In July 2011, the director of the exempt organizations office, Lois Lerner, told the employees to stop singling out Tea Party groups and instead focus on whether any group might be more active in politics than social welfare, the report said. Yet, just a few months later, the employees were back to using ideological tests.