What powers did the Indian Removal Act of 1830 give President Jackson?

The primary purpose of the Indian Removal Act of 1830 was the relocation of Southeastern Native-American tribes west of the Mississippi. This would free up rich, fertile land for President Jackson's core constituency of Southern farmers, the very people who'd helped him get elected. The discovery of gold in east Georgia was also a major factor behind the new policy. Strange as it may seem today, Jackson actually thought that by the policy of relocation he was protecting Southeastern tribes from the kind of decline experienced by their Northern counterparts.
The Act gave Jackson the authority to negotiate treaties with individual tribes such as the Chickasaw and the Choctaw in pursuance of the overriding goal of removal. To that end, the Act also authorized the President to exchange lands with native tribes rather than simply seize their land. Technically, then, the provisions of the Act were totally voluntary; the Administration would offer to exchange land with the native tribes to facilitate their resettlement west of the Mississippi, and it was entirely up to the tribes to decide whether or not they would accept such an offer.
In actual fact, however, Jackson turned a blind eye to continued acts of intimidation by white settlers against Native-Americans, believing that those who didn't agree to resettlement should effectively be denied the full protection of the law. In choosing to look the other way while native tribes continued to be driven from their land, Jackson was not only complicit in the numerous atrocities carried out against them, he was also violating the terms of his own legislation, which was supposed to be based on the free and voluntary exchange of land.