What is market economy status? After reading several articles on China losing WTO dispute against EU for market economy status, I could not understand what is the market economy status in this case?
One such newspaper article is here
My question: Does WTO assign economy status?
Market economy status that World Trade Organization (WTO) uses is not really an economic status per se. Rather its a 'legal' status that determines how other WTO members are allowed to treat country with regards to imposing tariffs or other protective measures. The reason why this status exist is that in past non-market economies such as
Union of Soviet Socialist Republics (USSR) were considered to be engaged in dumping since they heavily subsidized their economically nonviable industries.
WTO has created some special provisions made in case such economy would want to join WTO, and such economies with non-market status could be subject to some extra protectionists policies (in this case especially anti-dumping policies) in contrary to original WTO mission of promoting the free trade.
Such status has nothing to do in principle with whether the country is actually predominantly based on market economy or not. Its rather just a term WTO uses in its policy. A legalistic language does not need to conform to economic reality, for example often many taxes from economic perspective are legally not considered taxes but have different status such as social contributions in many countries.
According to professor Li Jinshan:

The term “non-market economy state” originally appeared in the 1930 Tariff Act of the United States, as opposed to “state-controlled economy”. For the US, socialist countries totally monopolized the national economy and controlled prices of all merchandises. Hence, the prices of exported goods were untrue, and importing countries needed to seek a third country’s data to be a reference to calculate the market price for anti-dumping investigations and for determining anti-dumping duties on goods from the socialist countries. .... In accordance with these criteria, all socialist countries were listed as “non-market economy states”. The EU, Canada and other WTO members followed the US in defining the concept of “non-market economy” and relevant criteria in their anti-dumping laws.

Also yes the WTO can decide whether economy has market economy status or not as its a legalistic term that does not need to correspond to whether economy is actually a market economy or not. In fact until recently countries could choose themselves how to treat China. As further argued by Li Jinshan:

In its WTO accession agreement, China agreed that other WTO members could treat it as a non-market economy until 2015. This classification was agreed in the US-China 1999 bilateral agreement and was multilateralized as part of China’s WTO entry protocol. This classification is vital to one area of trade policy: dealing with dumping allegations against Chinese firms.

So not only WTO can give the economy such status it can even let some countries decide whether they will treat an economy under such status or not. In fact as the article you link mentioned this is all about EU treating China as non-market economy. Of course, countries might dispute this at WTO (it’s in some ways similar procedure to having dispute at a court), but in this case China lost the dispute.