Background
The Interstate Commerce Commission, established in 1887, was an ineffective way to restrain railroads who could just appeal its decisions in federal courts, which could take 10 years. Congress finally pass the Elkins Act in 1903. This restrained rebate evil and hefty fines would be given out to the railroads that gave out the rebates and the shippers that received them. The Hepburn Act of 1906 was another effective legislation that restricted free passes and bribes. These acts allowed the Interstate Commerce Commission to grow larger to include express companies, sleeping-car companies, and pipelines. It now had the authority and power to nullify existing rates and to arrange maximum rates.
Political cartoon analysis
Here TR is dressed as a hunter to hunt down the rampant and large corruption from the railroads, which is represented as the big and dangerous bear. The bear is trying to protect himself and his home, which is titled rebate system. This signifies the Elkins Act of 1903 that Congress passed to restrain rebates and give out great fines for those who gave out rebates and those who accepted them. Railroad regulation was badly needed so Roosevelt had to work hard, or "fight for his life," to fix it.