While there is an act, titled the Presidential Records Act, which requires the President of the United States to preserve records and other laws governing the federal government. This serves as a form of checks and balances to prevent the president and his advisers from shielding documentary information from public view
It is important to realize that this law does not apply to print outs or widely circulated documents. Moreover, the copy of the State of the Union that she was given is not a governmental record. Therefore, House Speaker Pelosi did not violate the Presidential Records Act, nor any other federal law.
However, it is open to debate whether Pelosi's action was appropriate, though I will not comment on that.