Key congressional supporters of network neutrality plan to reintroduce their legislation soon, hoping AT&T's decision to agree to treat all online content the same to gain Federal Communications Commission approval of its purchase of BellSouth Corp. elevates the policy into law. And AT&T's pledge not to discriminate among Internet content, contained largely in a two-sentence paragraph, may rob neutrality opponents of one of their most effective arguments: that the issue is too vague to be precisely defined.