David Anderson QC said his "central concern" about the proposals first unveiled by David Cameron in early September was: "Where are the courts?"
Temporary Exclusion Orders are one of the measures in the counter terrorism bill published by Theresa May.
It also includes tougher powers to stop people going abroad to fight.
It will include plans to stop some British citizens returning to the UK, and others from leaving the country.
In other developments on Wednesday:
Analysis by Political Correspondent Robin Brant
The government proposes the law, parliament passes it, then David Anderson reviews it - and sometimes makes recommendations. That's the usual sequence of events.
But today the independent reviewer was criticising the process before the new Counter-Terror and Security Bill was published.
The QC used his customary polite, sometimes understated, tone - but this was a criticism of politicians whom he said hadn't fully thought through some of the proposals announced in early September.
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Mrs May's new measures to tackle terrorism come days after she said the UK faces a "greater" terror threat than ever before.
The measures include requiring airlines to pass on details of their passengers and changes to the way TPIMs - Terrorism Prevention and Investigation Measures - work to monitor terror suspects who cannot be prosecuted.
But campaigners have condemned it, saying it threatens civil liberties.
'A more sensible way'
Mr Anderson - appointed by the government to be its independent reviewer of terrorism legislation - said the new anti-terror legislation was "nothing like as dramatic" as David Cameron had proposed earlier this year.
He told the Joint Committee on Human Rights the original plan to block suspected British jihadists returning from Iraq and Syria as "an announcement waiting for a policy".
But he said it soon became clear such a move would "neither legally or practically" work and the current plan was now much "closer to managed return".
He argued there could be "a more sensible" way of dealing with some people suspected of being involved in terrorist activities.
"One could look at it in terms of young, possibly vulnerable people caught up with the wrong crowd in Syria - didn't really know exactly what they were doing," he said.
"Do you want to throw the book at them straight away in terms of arrest and charge? Or is there something to be said, even though you do suspect them of having fought, of keeping them under a very light regime where they might have to report daily to a police station?
The new Counter-Terrorism and Security Bill includes:
"They might have to notify their residence; they might have to go along to meetings with probation or with some similar which perhaps might be for some people be a more sensible way of dealing with them than putting them straight into the criminal justice process."
Mr Anderson said the use of exclusion orders would require the cooperation of carriers, such as airlines and of states where these people might find themselves.
"But certainly presented with an order at the check-in desk, the person might say: 'I want to come home,' or decide not to come home," he said.
"The concern I have about this power and the central concern about it is: where are the courts in all of this?
"If the home secretary wants to impose a TPIM she has to go to the court first and if the court says she's got it wrong, it will say so.
"One will want to look very carefully to see if this is a power that requires the intervention of the court at any stage, or whether it's simply envisaged as something the home secretary imposes.
"If one is abroad when this order is served on you, then it's a little difficult to see in practical terms how a right to judicial review could be exercised."
Mr Anderson spoke out as a week-long counter-terrorism awareness campaign enters its third day.
'Changing threats'
The UK's terror threat level remains "severe" after it was upped from "substantial" earlier this year in response to conflicts in Iraq and Syria.
Speaking ahead of the bill's publication, Mrs May said: "We are in the middle of a generational struggle against a deadly terrorist ideology. These powers are essential to keep up with the very serious and rapidly changing threats we face.
"This bill includes a considered, targeted set of proposals that will help to keep us safe at a time of very significant danger by ensuring we have the powers we need to defend ourselves."
The government wants to "fast-track" the bill through Parliament, citing the need to tackle the direct threat posed by the group calling itself Islamic State (IS) and the increasing number of Britons travelling to Iraq and Syria to fight on its behalf.
But shadow home secretary Yvette Cooper said more was needed to be done to stop British citizens from being radicalised and to deal with any threat this posed to national security.
Amnesty International called the powers "draconian", adding none of the measures seemed "properly thought through".
And Shami Chakrabarti, director of human rights group Liberty, said: "Yet again, politicians resort to high talk and rushed legislation in an attempt to look tough in the face of terrorism. Another chilling recipe for injustice and resentment by closing down the open society you seek to promote."
The Home Office says communications data has played a major role in "every Security Service counter-terrorism operation over the last decade" but gaps in the UK's access to such information need to be filled.
Mrs May has warned that even the new data retention powers will not fully address the threat, reiterating the need for a Communications Data Bill to bring in more wide-ranging web monitoring powers.
That bill - labelled a snooper's charter by critics - was scrapped following Lib Dem opposition.
Technology firms said there had been insufficient consultation on the more limited proposals in the bill requiring firms to keep information to help the authorities to match internet protocol (IP) addresses to an individual user or a device.
The Home Office said it had met internet service providers and other groups to discuss the measures but the Internet Services Providers Association said there had been "a distinct lack of engagement" with the industry.
Ministers want to amend legislation passed earlier this year to require firms to retain data, including that "required to identify the sender or recipient of a communication, the time or duration of a communication, the type, method or pattern of communication and the telecommunications system used".
However, the bill stresses that the content of messages and details that would "explicitly identify" what websites someone had visited would not have to be stored.
On Tuesday a report into last year's killing of Fusilier Lee Rigby raised questions about whether social network providers should have to report details of extremist activity.
David Cameron said companies had a "social responsibility" to act on terrorist material posted online after the report detailed how Michael Adebowale, one of two men convicted of Mr Rigby's murder, spoke on Facebook about wanting to murder a soldier.
Facebook said it did not allow terrorist content and aimed to stop it.
Concerns about plans to exclude people from the UK if they go abroad to fight with extremist groups have been raised by the UK's reviewer of terror laws.