tamper with

tamper with (something)

To make harmful or subversive alterations to something; to meddle or interfere with something. Investigators concluded that someone had tampered with the control unit of the machine. He's been accused of tampering with the committee tasked with selecting successful applicants. The locks have not been tampered with and there is no sign of a break-in anywhere on the premises.
See also: tamper
Farlex Dictionary of Idioms.

tamper with someone or something

to fiddle with someone or something; to meddle with someone or something. I've got him believing just what I want him to believe. Don't tamper with him. Please don't tamper with the thermostat.
See also: tamper
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

tamper with

1. Interfere or meddle, especially in a harmful way. For example, If you tamper with that lock it's sure to break. [c. 1600]
2. Engage in improper or secret dealings, as in He was accused of tampering with the jury. [c. 1600]
See also: tamper
The American Heritage® Dictionary of Idioms by Christine Ammer.

tamper with

v.
To interfere with something in a harmful manner: Someone has been tampering with my mail—these letters have been opened! When jurors reported that they had been offered bribes, the judge told the defense not to tamper with the jury.
See also: tamper
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • (someone or something) promises well
  • accompanied by
  • accompanied by (someone or something)
  • accompany
  • (have) got something going (with someone)
  • a ghost at the feast
  • a/the feel of (something)
  • (I) wouldn't (do something) if I were you
  • a straw will show which way the wind blows
  • a crack at (someone or something)
References in periodicals archive
If according to the referee, who can always take a second look at the television footage, an attempt has been made to tamper with the ball, he should punish the offender.
Biting off more than he could chew
That could give the enemy an opportunity to tamper with water supplies.
Message in a bottle
Afridi, who was left out of the side at The Oval, told Indian newspaper Times Now: "You have to tamper with the ball in order to make it swing.
Cricket: It's OK to tamper, says Afridi; CRICKET: Reports say coach Fletcher went to see match referee before start of play
Along with Derrick, a Glamorgan steward claimed he witnessed Kirby tamper with the ball and he was called in front of the inquiry.
Derrick waits on inquiry into ball-tampering row
As a guest on CNBC's Topic A with Tina Brown, guest-hosted that particular evening by Howard Dean, Harris demonstrated how easy it is to tamper with votes when they are sent through this system.
Follow nonexistent the paper trail: the technological advances in electronic voting machines rise accountability questions about today's democratic process
As energy shortages lead to rolling blackouts in California and threaten other states, many experts fear that the dire situation will further embolden power thieves to divert current or tamper with meters.
When Power Corrupts
Moreover, because all computers make errors from time to time, "our methods work even against machines that we cannot actively tamper with," Lipton says.
Chinks in the digital armor: exploiting faults to break smart-card cryptosystems
Gul had earlier said that he had seen Anderson tamper with the ball during the Pakistan-England Test series in England last year, while Broad during the Ashes series.
Gul says ball tampering comments were misconstrued