A quarter of a century ago, a former president fled from the Philippines after a revolution. This week, another former president was stopped trying to leave in what President Benigno Aquino hopes will be the start of a new revolution.

Aquino, who swept to power last year on a platform of ending poverty by fighting corruption, has his sights on a high-profile target -- his predecessor Gloria Macapagal Arroyo, who faces accusations of election fraud, bribery and kickbacks.

That's not so unusual in the Philippines. Arroyo herself prosecuted corruption charges against her predecessor, Joseph Estrada, who was convicted of plunder and sentenced to life imprisonment.

But Arroyo quickly pardoned and freed Estrada, who had been under house arrest in one of his luxury villas for nearly six years while under trial, and he came second behind Aquino in the 2010 election.

Aquino says there will be no pardons. The case is central to his pledge to end the culture of patronage and immunity that has allowed corruption to flourish and the elite to perpetuate their power -- and even helped him to office.

The rules of the game, I think, will change, Ramon Casiple, executive director of the Institute for Political and Electoral Reforms, told Reuters.

There is a big possibility we will see reforms starting in his term but it will not be finished in five years. Many things, however, can be done during this period to weaken patronage system and modernize the democratic system.

BLOCKED FROM LEAVING

Arroyo had been blocked from leaving the country but in a day of drama on Tuesday, the Supreme Court issued a temporary restraining order on the government's travel ban.

Arroyo, who had not been charged with anything, turned up at the airport in a wheelchair and her neck in a brace, aiming to fly overseas for medical treatment, but she and her husband were turned back.

The government said it had not received a copy of the court order and the travel ban stood.

That prompted accusations that the government was creating a constitutional crisis by defying the Supreme Court, which is due to hold a special session on Friday to hear the government's motion.

On Friday, the government sought a new ban on Arroyo leaving the country after the election commission filed electoral sabotage charges against the former president.

Aquino and the court, dominated by Arroyo appointees, have been at odds since before he took office.

Arroyo controversially appointed a former chief of staff as chief justice after last year's presidential election had been held but before she left office. Aquino pointedly took his oath of office from another justice.

Last year, the court ruled against the government in three major cases, including plans for a commission to investigate Arroyo.

GOING AFTER THE ELITE?

In the Philippines' recent history, holding members of the elite accountable is rare.

The late dictator Ferdinand Marcos was forced to step down by a people's power uprising and fled from the country in 1986.

His wife, Imelda, has never spent a day in jail over any of the hundreds of corruption cases she faced. Known for her expansive collection of shoes and jewellery, Marcos is serving a second term in Congress. Her son is a senator and an elder daughter is a provincial governor.

During the 1992-98 presidency of Fidel Ramos two congressmen were jailed -- one for gun smuggling and the other for raping a minor.

But since then no politician, general, or wealthy businessman has been jailed for corruption, given Estrada's pardon.

Despite his conviction for plunder, Estrada remains extremely popular and his family influential. One of Estrada's sons is a senator and another sits in Congress. His wife used to be a senator.

Arroyo is a Congresswoman. Her two sons are also members of Congress, as is a brother-in-law.

INVESTMENT CLIMATE

The dynastic nature of politics extends into business, where family-based conglomerates dominate. The resulting opaque business and legal environment is seen as a major disincentive to foreign investment which lags many regional rivals.

Last year, the Philippines attracted just $1.7 billion (1.0 billion pounds), or 2.3 percent of the $75.6 billion of the net foreign direct investment that flowed into the 10 members of the Association of South East Asian Nations.

The Heritage Foundation, in its 2011 Index of Economic Freedom, said there was a long-standing culture of corruption in the Philippines and the judicial system was weak.

NO CHANGE OR BEST BET?

Aquino is also part of the elite. His mother, Cory, was the champion of Philippine democracy who defeated Marcos in the 1986 presidential election after her husband, a prominent Marcos opponent, was murdered.

Aquino's family name was his biggest asset in his election victory last year.

Not all see purely noble intentions in Aquino's actions but rather the playing out of rivalries within the elite. He is a nephew of one of the staunchest allies of Ferdinand Marcos. Arroyo and her husband are both members of landowning families that make up the Philippine ruling class.

I don't see any change; the same type of things happening before are taking place again, Benito Lim, political science professor at the Ateneo de Manila University, told Reuters.

Aquino is showing that he is trying to go after the elites, but these are the elites who are his enemies. He is only showing us how the political elites behave.

The president has been criticized for the appointment of friends to government jobs, and for being too heavily influenced by his family connections.

While Aquino has made efforts to counter various strongmen and kingpins, he has been cautious because there were groups within his circle who resisted such moves, Casiple said.

Don't expect him to be an activist, he said.

He is not a hero on a white horse, but he is our best bet to introduce reforms in our political system.

(Additional reporting by John Mair; Editing by Robert Birsel and Raju Gopalakrishnan)