What is Mann-Elkins Act?

Legal Definition
The Mann–Elkins Act was a 1910 United States federal law that was among the Progressive era reforms. The Act extended the authority of the Interstate Commerce Commission (ICC) to regulate the telecommunications industry, and designated telephone, telegraph and wireless companies as common carriers. During President William Howard Taft's administration, the federal government moved to strengthen its regulatory control over the railroad industry by the passage of the Mann–Elkins Act.

Supported by Taft, the law also expanded on the powers granted to the ICC in the 1906 Hepburn Act. The ICC was authorized to investigate proposed railroad rate increases and suspend them if warranted. The "long-and-short haul" clause of the original Interstate Commerce Act (1887) was strengthened to prohibit railroads from charging passengers more for a short distance trip, compared to a longer distance ride, over the same route, unless specifically approved by the ICC.

The Act also created the short-lived United States Commerce Court for adjudication of railway disputes. The Court presided until 1913, when it was abolished by Congress.
-- Wikipedia