When a concern is raised in the House about a breach of privilege concerning an order to produce a document or, in this case, to summon a witness, the House can refer the matter for examination to a committee, which is generally the Standing Committee on Procedure and House Affairs. The House can give an order. In his case, it has already done so, but it could amend that order if it is of the opinion that the matter is one of concern.
The increasing range of measures can include summoning an individual to the bar of the House, declaring that an individual is in contempt of Parliament, or withdrawing confidence in the government, as was done in 2011.