President Yanukovych was removed from power on 22 February 2014, a year or so before his term of office was due to end. On 4 February this year, the Verkhovna Rada (Ukrainian Parliament) passed a law titled 'On the Divestment of Viktor Yanukovych of the Title of President of Ukraine'. This law, authored by amongst others Yulia Tymoshenko, his opponent in the 2010 presidential election, sought to divest him of the title of 'President of Ukraine', which past presidents are normally allowed to keep for life.
But President Poroshenko has refused to sign this law. Instead, he referred it to the Constitutional Court and asked the Court to certify that it contravenes the Constitution. His grounds for doing so is that "the title of President of Ukraine is protected by law and retained for life, unless the president of Ukraine in question has undergone the procedure of impeachment" (see Poroshenko sees law stripping Yanukovych of presidential rank as unconstitutional).
The grounds cited by President Poroshenko are based on Article 105 of the Constitution of Ukraine, which says:
"The title of President of Ukraine is protected by law and is reserved for the President for life, unless the President of Ukraine has been removed from office by the procedure of impeachment".
Article 111 of the Constitution specifies the lengthy procedure of impeachment which must be followed if a president is to be removed from power before the end of his term of office without violating the Constitution. Clearly, President Poroshenko doesn't believe that Yanukovych was subject to this procedure in February 2014.
British Government said Yanukovych was impeached
The British Government at the time said the opposite: then Ministers assured Parliament that Yanukovych's removal had been effected in accordance with the Ukranian Constitution and there was no reason to question the legitimacy of the new regime in Kiev.
On 24 February 2014, for example, Foreign Secretary William Hague told the House of Commons that two days earlier the Rada had "voted ... to impeach the President". Foreign Office Minister Lord Wallace repeated this message in the House of Lords.
And so did Foreign Office Minister Baroness Warsi on 20 March 2014, in answer to a question from Lord Stoddart of Swindon, who had asked the Government
"what steps they took to satisfy themselves that the removal from office of President Yanukovych was carried out in accordance with Article 111 of the Ukranian Constitution".
The procedure of impeachment
According to the procedure of impeachment defined in Article 111, the Rada must establish a special investigatory commission to formulate charges against the president, seek evidence to justify the charges and come to conclusions about the president's guilt for the Rada to consider. To find the president guilty, at least two-thirds of Rada members must assent.
Prior to a final vote to remove the president from power, the procedure requires
•the Constitutional Court of Ukraine to review the case and certify that the constitutional procedure of investigation and consideration has been followed, and
•the Supreme Court of Ukraine to certify that the acts of which the President is accused are worthy of impeachment.
To remove the president from power, at least three-quarters of Rada members must assent.
The Rada didn't make any pretence of following this procedure. No investigatory commission was established and the Courts were not involved. On 22 February 2014, the Rada simply passed a resolution purporting to remove Yanukovych from office in accordance with the Constitution.
It was therefore reasonable for President Poroshenko to refer the law seeking to divest Yanukovych of his title of 'President of Ukraine' to the Constitutional Court on the grounds that he wasn't impeached in accordance with the procedure laid down in the Constitution.
An unconstitutional coup d'etat?
In doing so, Poroshenko comes close to confirming that the removal of Yanukovych from power in February 2014 was an unconstitutional coup d'etat.
It is true that the Rada can also remove an elected president from power under Article 110 of the Constitution if he is deemed unfit to exercise power due to ill health - and he/she may die or resign. But Yanukovych didn't die or resign, nor was he unable to exercise his powers due to ill health, so the only constitutional means of removing him from power before the end of his term was by following the impeachment procedure enshrined in Article 111. It wasn't followed.
The British Government lied to Parliament in saying that Yanukovych was impeached and removed from power in accordance with the Constitution. That the British Government lied is confirmed by President Poroshenko's action in referring this law to the Constitutional Court on the grounds that Yanukovych wasn't impeached in accordance with the Constitution.