tamper vi1 : to bring improper influence to bear (as by bribery or intimidation) used with with [ed with the jurors]
2 : to alter or interfere in an unauthorized or improper manner used with with [ed with evidence]
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.