HARTFORD — The state ­Supreme Court ruled Monday that criminal defendants ­accused of playing a role in the killing of a witness cannot then argue that the witness’s statements are inadmissible at trial.

The court’s 7-to-0 decision came in the case of former Bloomfield resident Anthony Thompson, who is serving a 70-year prison sentence for killing a man and wounding two other people in a 2005 bar fight in Hartford.

He also awaits trial on charges he orchestrated the killing of a witness who had told police that Thompson was the bar shooter.

In appealing his murder and assault convictions, Thompson asserted that the trial judge wrongly ­allowed into evidence both the statement of the slain witness and evidence that Thompson planned the killing of the witness.

He said allowing the statement violated his constitutional right to confront witnesses and broke rules against hearsay evidence.

The Supreme Court rejected Thompson’s arguments and upheld his convictions. Justices agreed with prosecutors and the judge in Thompson’s trial that there was enough evidence that Thompson was complicit in the witness’s death, and they cited a 1982 ruling by the Second US Circuit Court of Appeals in a case involving the killing of a witness in a drug crime prosecution.

‘‘If a witness’s silence is procured by the defendant himself . . . the defendant cannot then assert his confrontation clause rights in order to prevent prior grand jury testimony of that witness from being admitted against him,’’ the appeals court said. ‘‘Any other result would mock the very system of justice the confrontation clause was designed to protect.’’

Justices also quoted from a ruling by the US Circuit Court of Appeals for the District of ­Columbia.

‘‘The defendant who has ­removed an adverse witness is in a weak position to complain about losing the chance to cross-examine him,’’ the ­appeals court said.

Prosecutors said Thompson fatally shot O’Neil Robinson, 34, of Bloomfield, and wounded two others inside the Cleveland Cafe in Hartford’s North End in the early morning hours of Valentine’s Day 2005. ­Robinson was a father of 12.

Two years later and before Thompson’s trial, a witness to the shooting — Asher Glace, a 21-year-old nursing student — was shot to death in the driveway of her Hartford home. ­Glace had given a statement to police identifying Thompson as the shooter.

Thompson’s lawyer, Lisa Steele, said she is disappointed with the Supreme Court’s ruling and is considering an ­appeal to the US Supreme Court.

She said the trial judge, in determining that Thompson played a role in the killing of Glace, relied on a lower ‘‘preponderance of evidence’’ standard instead of the higher ‘‘clear and convincing’’ evidence standard.

The evidence included statements by a jailhouse informant.