A government department has been branded "shambolic" by MPs over its handling of a contract for court language services in England and Wales.
The Ministry of Justice ignored fears that standards would fall when the contract was outsourced, the Commons justice committee said.
Some interpreters failed to turn up, leading to cancelled trials, and others mistranslated evidence, it said.
Ministers said "dramatic improvements" had followed the initial problems.
The contract for language services began in early 2012.
The translation and interpreter services - for victims, witnesses and defendants - immediately ran into difficulties, MPs said.
The committee said the Ministry of Justice (MoJ) had not had a sufficient understanding of the complexities of court interpreting and translation work before it decided to put the services out to tender.
"The Ministry of Justice's handling of the outsourcing of court interpreting services has been nothing short of shambolic," committee chairman Sir Alan Beith said.
He said the MoJ "did not have an adequate understanding of the needs of courts, it failed to heed warnings from the professionals concerned and it did not put sufficient safeguards in place to prevent interruptions in the provision of quality interpreting services to courts".
The committee said this was a particular cause for concern as the MoJ was about to launch a far-reaching competitive process for probation services as part of a "rehabilitation revolution".
The committee said the government department ignored warnings about how complex the work was before it signed a five-year deal with Applied Language Solutions, which has now been acquired by the company Capita.
It said the Ministry of Justice and the contractor "buried their heads in the sand" amid mounting problems.
MPs said the department may have also committed a contempt of Parliament by instructing court staff not to co-operate with its inquiry.
Justice Minister Helen Grant said that while there had been "significant" issues at the start of the contract last year, "swift and robust action" had led to "dramatic improvements".
She said: "The vast majority of interpreter bookings are now being completed and complaints have fallen considerably.
"The changes we have made have led to major savings for taxpayers, totalling £15m in the first year, and we continue to monitor the contract on a daily basis and demand continuing progress."